Higher Unit 2 EF 1.4 Higher Unit 3 Vectors and Scalars Properties of vectors Adding / Sub of...

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Higher Unit 2 EF 1.4

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Higher Unit 3Higher Unit 3

Vectors and ScalarsProperties of vectorsAdding / Sub of vectorsMultiplication by a Scalar

Position VectorCollinearity

Unit Vector

Exam Type Questions

Section Formula

3D Vectors

Properties 3DSection formulaScalar Product

Angle between vectorsPerpendicular

Component Form

Properties of Scalar Product

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Higher Unit 2 EF 1.4

Vectors & Scalars

A vector is a quantity with

BOTH magnitude (length) and direction.

Examples : Gravity

Velocity

Force

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Higher Unit 2 EF 1.4

Vectors & Scalars

A scalar is a quantity that has

magnitude ONLY.

Examples : Time

Speed

Mass

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Higher Unit 2 EF 1.4

Vectors & Scalars

A vector is named using the letters at the end of the directed line segment

or

using a lowercase bold / underlined letter

This vector is named

AB,,,,,,,,,,,,,,

AB,,,,,,,,,,,,,,

or u

or u

uu

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Higher Unit 2 EF 1.4

Vectors & Scalars

A vector may also be

represented in component form.

4

2CD w

,,,,,,,,,,,,,,

w

xAB d

y

,,,,,,,,,,,,,,

z

2

1FE z

,,,,,,,,,,,,,,

Also known as column vector

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Higher Unit 2 EF 1.4

Magnitude of a Vector

A vector’s magnitude (length) is represented by

or PQ u,,,,,,,,,,,,,,

A vector’s magnitude is calculated using Pythagoras

Theorem.

2 2PQ u a b ,,,,,,,,,,,,,, u

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Higher Unit 2 EF 1.4

Vectors & Scalars

Calculate the magnitude of the vector.

4

2CD w

,,,,,,,,,,,,,,w

2 2w a b

2 24 2w

20w

4 5 2 5w

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Higher Unit 2 EF 1.4

Vectors & Scalars

Calculate the magnitude of the vector.

4

3PQ

,,,,,,,,,,,,,,

2 2w a b

2 2( 4) 3w

16 9w

5w

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Higher Unit 2 EF 1.4

Equal Vectors

Vectors are equal only if they both have

the same magnitude ( length ) and direction.

Vectors are equal if they have

equal components.

For vectors

and , if then and a c

u v u v a c b db d

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Higher Unit 2 EF 1.4

Equal Vectors

By working out the components of each of the vectors determine which are equal.

a

b c

d

ef

g

h

a

g

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Higher Unit 2 EF 1.4

Addition of Vectors

Any two vectors can be added in this way

a

b

a + b

b

2

4

6

3

8

1

Arrows must be

nose to tail

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Higher Unit 2 EF 1.4

Addition of Vectors

Addition of vectors

3 2Let and

4 5AB BC

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

A

B

C

Then + AB BC AC,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

5So

1AC

,,,,,,,,,,,,,,

3 2 5 +

4 5 1

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Higher Unit 2 EF 1.4

Addition of Vectors

In general we have

If and then a c

u vb d

For vectors u and v

+ + = a c a c

u vb d b d

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Higher Unit 2 EF 1.4

Zero Vector

The zero vector

1 If AB

2

,,,,,,,,,,,,,,

1 1 0 AB + BA + =

2 2 0

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

0 is called the zero vector, written 0

0

1 then BA

2

,,,,,,,,,,,,,,

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Higher Unit 2 EF 1.4

Negative Vector

Negative vector

is the negative of BA AB,,,,,,,,,,,,,,,,,,,,,,,,,,,,

0 u u u u

For any vector u

If then a a

u ub b

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Higher Unit 2 EF 1.4

Subtraction of Vectors

Any two vectors can be subtracted in this way

u

v

u - v

6

3

5

0

Notice arrows nose

to nose

1

3

v

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Higher Unit 2 EF 1.4

Subtraction of Vectors

Subtraction of vectors

6 2Let and

5 4a b

Then ( )a b a b

6 2 4 -

5 4 1

6 2 4

5 4 1

a b

a - b

Notice arrows nose

to nose

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Higher Unit 2 EF 1.4

Subtraction of Vectors

In general we have

If and then a c

u vb d

For vectors u and v

= a c a c

u vb d b d

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Higher Unit 2 EF 1.4

Multiplication by a Scalar

Multiplication by a scalar ( a number)

If a vector then x kx

v kvy ky

The vector is parallel to vector ( different size )kv v

Hence if u = kv then u is parallel to v

Conversely if u is parallel to v then u = kv

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Higher Unit 2 EF 1.4

Multiplication by a Scalar

Multiplication by a scalar

Write down a vector

parallel to a

Write down a vector

parallel to ba

b

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Higher Unit 2 EF 1.4

Multiplication by a Scalar

Show that the two vectors are parallel. 6 18

then z 9 27

w

If z = kw then z is parallel to w

18 6 = 3

27 9z

3z w

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Higher Unit 2 EF 1.4

Multiplication by a Scalar

Alternative method.

6 18 then z

9 27w

If w = kz then w is parallel to z

6 181 =

9 273w

1

3w z

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Higher Unit 2 EF 1.4

Unit Vectors

For ANY vector v there exists

a parallel vector u of magnitude 1 unit.

This is called the unit vector.

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Higher Unit 2 EF 1.4

Unit Vectors

Find the components of the unit vector, u , parallel to vector v , if

So the unit vector is u

3

4v

2 23 4v

5v 31

45u

3

5 4

5

v

u

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Higher Unit 2 EF 1.4

Position Vectors

A is the point (3,4) and B is the point (5,2).

Write down the components of

OA,,,,,,,,,,,,,,

OB OA ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

3

4

B

A

OB ,,,,,,,,,,,,,, 5

2

AB ,,,,,,,,,,,,,, 2

2

5 3 2

2 4 2

Answers

the same !

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Position Vectors

is called the position vector of the point A

relative to the origin , written as

OA,,,,,,,,,,,,,,

O a

is called the position vector of the point B

relative to the origin , written as

OB,,,,,,,,,,,,,,

O b

AB ,,,,,,,,,,,,,,

b a AO OB ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

a b

B

A

a

b0

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Higher Unit 2 EF 1.4

Position Vectors

where and are the position vectors of and .

AB b a

a b A B

,,,,,,,,,,,,,,

B

A

a

b0

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Higher Unit 2 EF 1.4

Position Vectors

If P and Q have coordinates (4,8) and (2,3)

respectively, find the components of

2 4

3 8

PQ,,,,,,,,,,,,,,

2

5

PQ q p ,,,,,,,,,,,,,,

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P

Q

O

Position Vectors

Graphically

P (4,8)

Q (2,3)

= PQ,,,,,,,,,,,,,, 2

5

p

q

q - p

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Higher Unit 2 EF 1.4

Collinearity

Reminder !

If , where is a scalar, then is parallel to .AB kBC k AB BC,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Points are said to be collinear if they lie on the same straight line.

For vectors

If B is also a point common to both AB and BC then

A,B and C are collinear.

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Higher Unit 2 EF 1.4

BC c b ,,,,,,,,,,,,,,

Prove that the points A(2,4), B(8,6) and C(11,7) are collinear.

8 2

6 4

6

2

AB b a ,,,,,,,,,,,,,,

11 8

7 6

3

1

6 32

2 1AB

,,,,,,,,,,,,,,2BC,,,,,,,,,,,,,,

Collinearity

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Higher Unit 2 EF 1.4

Collinearity

Since 2 , is parallel to .AB BC AB BC,,,,,,,,,,,,,,,,,,,,,,,,,,,,

is a point common to both and

so , and are collinear.

B AB BC

A B C

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13I

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Higher Unit 2 EF 1.4

Section Formula

OS OA AS ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1

3OS OA AB ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1 ( )

3s a b a

2 1

3 3s a b O

A

B

1

2

S

a

b

3

s

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Higher Unit 2 EF 1.4

General Section Formula

OP OA AP ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

mOP OA AB

m n

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

( )m

p a b am n

n mp a b

m n m n

O

A

B

m

n

P

a

b

m + n

p

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Higher Unit 2 EF 1.4

If p is a position vector

of the point P that divides

AB in the ratio m : n

then

General Section Formula

n mp a b

m n m n

A

B

m

n

P

Summarising we have

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Higher Unit 2 EF 1.4

General Section Formula

2 3

5 5p a b

A

B

3

2P

A and B have coordinates (-1,5)

and (4,10) respectively.

Find P if AP : PB is 3:2

1 42 3

5 105 5p

2 12 5 5

2 6

102

58

8

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13K

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Higher Unit 2 EF 1.4

O

3D Coordinates

In the real world points in space can be located using a 3D coordinate system.

x

y

z

For example, air traffic controllers find the location a plane by its height and grid reference.

(x, y, z)

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Higher Unit 2 EF 1.4

O

3D Coordinates

Write down the coordinates for the 7 vertices

x

yzA

B

C

D

E

F

G

What is the coordinates of the vertex H so that it makes a cuboid shape.

6

2

1

(6, 1, 2)

(6, 0, 2)

(6, 0, 0)

(6, 1, 0)

(0, 1, 2)

(0, 0, 2)

(0,0, 0)

H(0, 1, 0 )

H

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Higher Unit 2 EF 1.4

3D Vectors

3D vectors are defined by 3 components.

z

For example, the velocity of an aircraft taking off can be illustrated by the vector v.

(7, 3, 2)

v

3

7

2

O x

y2

7

3

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Higher Unit 2 EF 1.4

O

3D Vectors

z

j

i x

y

k

Any vector can be represented in terms of the i , j and k

Where i, j and k are unit vectors

in the x, y and z directions.

1

= 0

0

i

0

= 1

0

j

0

= 0

1

k

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Higher Unit 2 EF 1.4

3D Vectors

z

Any vector can be represented in terms of the i , j and k

Where i, j and k are unit vectors

in the x, y and z directions.

(7, 3, 2)

v

3

7

2

O x

y v = ( 7i+ 3j + 2k )

7

= 3

2

v

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Higher Unit 2 EF 1.4

3D Vectors

Good NewsAll the rules for 2D vectors apply in the same way for

3D.

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Higher Unit 2 EF 1.4

Magnitude of a Vector

A vector’s magnitude (length) is represented by

v

A 3D vector’s magnitude is calculated using Pythagoras Theorem twice.

2 2 2v x y z

z v

2

3

1

O x

y2 2 23 2 1v

14v

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Higher Unit 2 EF 1.4

Addition of Vectors

Addition of vectors

3 2

Let 4 and 5

1 2

u v

Then + u v

3 2 5

4 + 5 1

1 2 3

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Higher Unit 2 EF 1.4

Addition of Vectors

In general we have

If and then

a d

u b v e

c f

For vectors u and v

+ + =

a d a d

u v b e b e

c f c f

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Higher Unit 2 EF 1.4

Negative Vector

Negative vector

is the negative of BA AB,,,,,,,,,,,,,,,,,,,,,,,,,,,,

0 u u u u

For any vector u

If then

a a

u b u b

c c

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Higher Unit 2 EF 1.4

Subtraction of Vectors

Subtraction of vectors

6 2

Let 5 and 4

3 2

a b

Then a b

6 2 4

5 - 4 1

3 2 1

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Higher Unit 2 EF 1.4

Subtraction of Vectors

If and then

a d

u b v e

c f

For vectors u and v

=

a d a d

u v b e b e

c f c f

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Higher Unit 2 EF 1.4

Multiplication by a Scalar

Multiplication by a scalar ( a number)

If a vector then

x kx

v y kv ky

z kz

The vector is parallel to vector ( different size )kv v

Hence if u = kv then u is parallel to v

Conversely if u is parallel to v then u = kv

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Higher Unit 2 EF 1.4

Multiplication by a Scalar

Show that the two vectors are parallel.

6 12

9 then z 18

12 24

w

If z = kw then z is parallel to w12 6

18 = 2 9

24 12

z

2z w

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Higher Unit 2 EF 1.4

Position Vectors

The position vector of a 3D point A is ,

usually written as

OA,,,,,,,,,,,,,,

a

3

= = 2

1

OA

,,,,,,,,,,,,,,a

z a

2

3

1

O x

y

A (3,2,1)

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Higher Unit 2 EF 1.4

Position Vectors

If R is (2,-5,1) and S is (4,1,-3) then RS s r ,,,,,,,,,,,,,,

4 2 2

1 5 6

3 1 4

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13M

HHM Ex13L

HHM Ex13N (Q1 - 14)

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Higher Unit 2 EF 1.4

Collinearity in 3D

Reminder !

If , where is a scalar, then is parallel to .AB kBC k AB BC,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Points are said to be collinear if they lie on the same straight line.

For vectors

If B is also a point common to both AB and BC then

A,B and C are collinear.

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13N (Q15 - 18)

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Higher Unit 2 EF 1.4

If p is a position vector

of the point P that divides

AB in the ratio m : n

then

General Section Formula

n mp a b

m n m n

A

B

m

n

P

Summarising we have

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13N (Q19-24)

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Higher Unit 2 EF 1.4

The scalar product

a

b

The scalar product is defined as being:

θ

cos a b a b

0 0 180

Must be

tail to tail

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Higher Unit 2 EF 1.4

The Scalar Product

Find the scalar product for a and b when

|a|= 4 , |b|= 5 when (a) θ = 45o (b) θ = 90o

cos a b a b = 4 5cos 45 o

20 10 2 2 10 2

2 2a b

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Higher Unit 2 EF 1.4

The Scalar Product

Find the scalar product for a and b when

|a|= 4 , |b|= 5 when (a) θ = 45o (b) θ = 90o

cos a b a b = 4 5cos90 o

20 0 0a b

Important : If a and b are perpendicular then

a . b = 0

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13O

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13O

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Higher Unit 2 EF 1.4

Component Form Scalar Product

If

1 1 2 2 3 3 a b a b a b a b

1 1

2 2

3 3

and

a b

a a b b

a b

then

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Higher Unit 2 EF 1.4

Angle between Vectors

To find the angle between two vectors we simply use the scalar product formula

rearranged

cos = a b

a b 1 1 2 2 3 3 cos =

a b a b a b

a b

or

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Higher Unit 2 EF 1.4

Angle between Vectors

Find the angle between the two vectors below.

cos = a b

a b

3 4

2 and 1

5 3

p q

2 2 23 2 5 38p 2 2 24 1 3 26q

3 +2j+5k and 4 + j+3kp i q i

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Higher Unit 2 EF 1.4

Angle between Vectors

Find the angle between the two vectors below.

cos = a b

a b

2 2 23 2 5 38p

2 2 24 1 3 26q 3 4 2 1 5 3 29p q

29 =

38 26 = 0.923

-1 o = cos (0.923) = 22.7

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Higher Unit 2 EF 1.4

Show that for

1 1 2 2 3 3 a b a b a b a b

3 1

2 and 2

1 7

a b

a and b are perpendicular

3 1 2 2 7 ( 1)a b

3 4 (-7) 0 a b

a . b =0

Perpendicular Vectors

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Higher Unit 2 EF 1.4

Perpendicular Vectors

0 cos = 0

a b

a b a b

Given a 0 and b 0 and a 0b

-1 o = cos (0) = 90

If a . b = 0 then a and b are perpendicular

Then

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13P

HHM Ex13Q

HHM Ex13R

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Higher Unit 2 EF 1.4

Properties of a Scalar Product

( )a b c a b a c

a ab b

Two properties that you need to be aware of

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Higher Unit 2 EF 1.4

Extra Practice

HHM Ex13U

Applications of Vectors

HHM Ex13S

HHM Ex13T

HHM Ex13T

Vectors

Strategies

Higher Maths

Click to start

Vectors Higher

Vectors

The following questions are on

Non-calculator questions will be indicated

Click to continue

You will need a pencil, paper, ruler and rubber.

Vectors Higher

The questions are in groups

Angles between vectors (5)

Points dividing lines in ratios

Collinear points (8)

General vector questions (15)

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Vectors Higher

General Vector Questions

Continue

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Hint

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Vectors Higher

Previous Next

Vectors u and v are defined by and

Determine whether or not u and v are perpendicular to each other.

3 2 u i j 2 3 4 v i j k

Is Scalar product = 0

3 2

2 3

0 4

u.v

3 2 2 3 0 4 u.v 6 6 0 u.v

0u.v Hence vectors are perpendicular

Hint

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Vectors Higher

Previous Next

For what value of t are the vectors and perpendicular ?2

3

t

u2

10

t

v

Put Scalar product = 0

2

2 10

3

t

t

u.v

2 2 10 3t t u.v 5 20t u.v

Perpendicular u.v = 0 0 5 20t

4t

Hint

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Vectors Higher

Previous Next

VABCD is a pyramid with rectangular base ABCD.

The vectors are given by

Express in component form.

, andAB AD AV,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

8 2 2AB ,,,,,,,,,,,,,,

i j k 2 10 2AD ,,,,,,,,,,,,,,

i j k

7 7AV ,,,,,,,,,,,,,,

i j k

CV,,,,,,,,,,,,,,

AC CV AV ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

CV AV AC ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

BC AD,,,,,,,,,,,,,,,,,,,,,,,,,,,,

AB BC AC ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Ttriangle rule ACV Re-arrange

Triangle rule ABC also

CV AV AB AD ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1 8 2

7 2 10

7 2 2

CV

,,,,,,,,,,,,,,5

5

7

CV

,,,,,,,,,,,,,,

9 5 7CV ,,,,,,,,,,,,,,

i j k

Hint

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Vectors Higher

Previous Next

The diagram shows two vectors a and b, with | a | = 3 and | b | = 22.

These vectors are inclined at an angle of 45° to each other.

a) Evaluate

i) a.a ii) b.b iii) a.b

b) Another vector p is defined by

Evaluate p.p and hence write down | p |.

2 3 p a b

cos0 a a a a 3 3 1 9 2 2 2 2 b b 8

cos 45 a b a b1

3 2 2 62

i) ii)

iii)

b) 2 3 2 3 p p a b a b 4 . 12 9 a a a.b b.b

36 72 72 180 Since p.p = p2 180 6 5 p

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Vectors p, q and r are defined by

a) Express in component form

b) Calculate p.r

c) Find |r|

- , 4 , and 4 3 p i j k q i k r i j

2 p q r

2 p q r - 4 2 4 3 i j k i k i j 8 5 -5 i j ka)

b) . - . 4 3 p r i j k i j . 1 4 1 ( 3) ( 1) 0 p r . 1 p r

c)2 24 ( 3) r 16 9 5 r r

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The diagram shows a point P with co-ordinates

(4, 2, 6) and two points S and T which lie on the x-axis.

If P is 7 units from S and 7 units from T,

find the co-ordinates of S and T.

Use distance formula ( , 0, 0)S a ( , 0, 0)T b

2 2 2 249 (4 ) 2 6PS a 249 (4 ) 40a 29 (4 )a

4 3a 7 1a or a

hence there are 2 points on the x axis that are 7 units from P

(1, 0, 0)S (7, 0, 0)T

i.e. S and T

and

The position vectors of the points P and Q are

p = –i +3j+4k and q = 7 i – j + 5 k respectively.

a) Express in component form.

b) Find the length of PQ.

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PQ,,,,,,,,,,,,,,

PQ ,,,,,,,,,,,,,,

q - p7 1

1 3

5 4

PQ

,,,,,,,,,,,,,,

-a)8

4

1

PQ

,,,,,,,,,,,,,,

8 4 i j k

2 2 28 ( 4) 1PQ ,,,,,,,,,,,,,,

b) 64 16 1 81 9

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PQR is an equilateral triangle of side 2 units.

Evaluate a.(b + c) and hence identify

two vectors which are perpendicular.

, , andPQ PR QR ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

a b c

( ) a. b c a.b a.c

cos60 a.b a b1

22 2 a.b 2 a.b

Diagram

P

RQ60° 60°

60°a b

c

NB for a.c vectors must point OUT of the vertex ( so angle is 120° )

cos120 a.c a c1

22 2

a.c 2 a.c

Hence ( ) 0 a. b c so, a is perpendicular to b + c

Table of

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Calculate the length of the vector 2i – 3j + 3k

22 22 ( 3) 3 Length 4 9 3

16

4

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Find the value of k for which the vectors and are perpendicular 1

2

1

4

3

1k

Put Scalar product = 0

1 4

2 3

1 1

0k

0 4 6 ( 1)k

3k

0 2 1k

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A is the point (2, –1, 4), B is (7, 1, 3) and C is (–6, 4, 2).

If ABCD is a parallelogram, find the co-ordinates of D.

AD BC ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

c b6 7

4 1

2 3

BC

,,,,,,,,,,,,,, 13

3

1

BC

,,,,,,,,,,,,,,

D is the displacement AD,,,,,,,,,,,,,,

from A

hence2 13

1 3

4 1

d11

2

3

d 11, 2, 3D

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If and write down the components of u + v and u – v

Hence show that u + v and u – v are perpendicular.

3

3

3

u1

5

1

v

2

8

2

u v4

2

4

u v

2 4

8 2

2 4

.

u v u v

look at scalar product

.

( 2) ( 4) 8 ( 2) 2 4

u v u v

8 16 8 0

Hence vectors are perpendicular

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The vectors a, b and c are defined as follows:

a = 2i – k, b = i + 2j + k, c = –j + k

a) Evaluate a.b + a.c

b) From your answer to part (a), make a deduction about the vector b + c 2 1

0 2

1 1

a.ba) 2 0 1 a.b 1a.b

2 0

0 1

1 1

a.c

b)

0 0 1 a.c 1a.c 0 a.b a.c

b + c is perpendicular to a

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A is the point ( –3, 2, 4 ) and B is ( –1, 3, 2 )

Find:

a) the components of

b) the length of AB

AB,,,,,,,,,,,,,,

AB ,,,,,,,,,,,,,,

b aa)1 3

3 2

2 4

AB

,,,,,,,,,,,,,, 2

1

2

AB

,,,,,,,,,,,,,,

2 2 22 1 ( 2)AB b) 4 1 4AB

9AB 3AB

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In the square based pyramid,

all the eight edges are of length 3 units.

Evaluate p.(q + r)

, , ,AV AD AB ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

p q r

Triangular faces are all equilateral

( ) p. q r p.q p.r

cos60 p.q p q1

23 3 p.q

1

24p.q

cos60 p.r p r1

23 3 p.r

1

24p.q

1 1

2 2( ) 4 4 p. q r ( ) 9 p. q r

Table of

Exact Values

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Points dividing lines in ratios

Collinear Points

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A and B are the points (-1, -3, 2)

and (2, -1, 1) respectively.

B and C are the points of trisection of AD.

That is, AB = BC = CD.

Find the coordinates of D 1

3

AB

AD

,,,,,,,,,,,,,,

,,,,,,,,,,,,,, 3AB AD ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3 b a d a

3 3 b a d a 3 2 d b a

2 1

1 3

1 2

3 2

d8

3

1

d (8, 3, 1)D

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The point Q divides the line joining P(–1, –1, 0) to R(5, 2 –3) in the ratio 2:1.

Find the co-ordinates of Q.

2

1

PQ

QR

,,,,,,,,,,,,,,

,,,,,,,,,,,,,, 2PQ QR ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

2 2 q p r q

3 2 q r p

5 1

2 1

3 0

3 2

q9

3

6

1

3

q (3, 1, 2)Q

Diagram P

QR

21

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a) Roadmakers look along the tops of a set of T-rods to ensure

that straight sections of road are being created.

Relative to suitable axes the top left corners of the T-rods are

the points A(–8, –10, –2), B(–2, –1, 1) and C(6, 11, 5).Determine whether or not the section of road ABC has been

built in a straight line.

b) A further T-rod is placed such that D has co-ordinates (1, –4, 4).

Show that DB is perpendicular to AB. AB ,,,,,,,,,,,,,,

b aa)6 2

9 3 3

3 1

AB

,,,,,,,,,,,,,, 14 2

21 7 3

7 1

AC

,,,,,,,,,,,,,,

andAB AC,,,,,,,,,,,,,,,,,,,,,,,,,,,,

are scalar multiples, so are parallel. A is common. A, B, C are collinear

b) Use scalar product6 3

9 3

3 3

. .AB BD

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

. 18 27 9 0AB BD ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Hence, DB is perpendicular to AB

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VABCD is a pyramid with rectangular base ABCD.

Relative to some appropriate axis, represents – 7i – 13j – 11k

represents 6i + 6j – 6k

represents 8i – 4j – 4k

K divides BC in the ratio 1:3

Find in component form.

VA,,,,,,,,,,,,,,

AB,,,,,,,,,,,,,,

AD,,,,,,,,,,,,,,

VK,,,,,,,,,,,,,,

VA AB VB ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

VK KB VB ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1 1 1

4 4 4KB CB DA AD ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

VK VB KB ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1

4VK VA AB AD ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

7 6 81

13 6 44

11 6 4

VK

,,,,,,,,,,,,,, 1

8

18

VK

,,,,,,,,,,,,,,

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The line AB is divided into 3 equal parts by

the points C and D, as shown.

A and B have co-ordinates (3, –1, 2) and (9, 2, –4).

a) Find the components of and

b) Find the co-ordinates of C and D.

AB,,,,,,,,,,,,,,

AC,,,,,,,,,,,,,,

AB ,,,,,,,,,,,,,,

b a6

3

6

AB

,,,,,,,,,,,,,, 2

1

2

1

3AC AB

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

a)

b) C is a displacement of from AAC,,,,,,,,,,,,,, 3 2

1 1

2 2

c (5, 0, 0)C

similarly5 2

0 1

0 2

d (7, 1, 2)D

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Relative to a suitable set of axes, the tops of three chimneys have

co-ordinates given by A(1, 3, 2), B(2, –1, 4) and C(4, –9, 8).

Show that A, B and C are collinear

AB ,,,,,,,,,,,,,,

b a1

4

2

AB

,,,,,,,,,,,,,, 3 1

12 3 4

6 2

AC

,,,,,,,,,,,,,,

andAB AC,,,,,,,,,,,,,,,,,,,,,,,,,,,,

are scalar multiples, so are parallel. A is common. A, B, C are collinear

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A is the point (2, –5, 6), B is (6, –3, 4) and C is (12, 0, 1).

Show that A, B and C are collinear

and determine the ratio in which B divides AC

AB ,,,,,,,,,,,,,,

b a4 2

2 2 1

2 1

AB

,,,,,,,,,,,,,, 6 2

3 3 1

3 1

BC

,,,,,,,,,,,,,,

andAB BC,,,,,,,,,,,,,,,,,,,,,,,,,,,,

are scalar multiples, so are parallel. B is common. A, B, C are collinear

2

3

AB

BC

,,,,,,,,,,,,,,

,,,,,,,,,,,,,,A

BC

23

B divides AB in ratio 2 : 3

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Relative to the top of a hill, three gliders

have positions given by

R(–1, –8, –2), S(2, –5, 4) and T(3, –4, 6).

Prove that R, S and T are collinear

RS ,,,,,,,,,,,,,,

s r3 1

3 3 1

6 2

RS

,,,,,,,,,,,,,, 4 1

4 4 1

8 2

RT

,,,,,,,,,,,,,,

andRS RT,,,,,,,,,,,,,,,,,,,,,,,,,,,,

are scalar multiples, so are parallel. R is common. R, S, T are collinear

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Angle between two vectors

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The diagram shows vectors a and b.

If |a| = 5, |b| = 4 and a.(a + b) = 36

Find the size of the acute angle

between a and b.

cos a.b

a b( ) 36 36 a. a b a.a a.b

25 a.a a a 25 36 a.b 11 a.b

11cos

5 4

1 11

cos20

56.6

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The diagram shows a square based pyramid of height 8 units.

Square OABC has a side length of 6 units.

The co-ordinates of A and D are (6, 0, 0) and (3, 3, 8).

C lies on the y-axis.

a) Write down the co-ordinates of B

b) Determine the components of

c) Calculate the size of angle ADB.

andDA DB,,,,,,,,,,,,,,,,,,,,,,,,,,,,

a) B(6, 6, 0) b)3

3

8

DA

,,,,,,,,,,,,,, 3

3

8

DB

,,,,,,,,,,,,,,

c).

cosDADB

DA DB

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,3 3

3 . 3 64

8 8

.DADB

,,,,,,,,,,,,,,,,,,,,,,,,,,,,

64cos

82 82 38.7

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A box in the shape of a cuboid designed with circles of different

sizes on each face.

The diagram shows three of the circles, where the origin represents

one of the corners of the cuboid.

The centres of the circles are A(6, 0, 7), B(0, 5, 6) and C(4, 5, 0)

Find the size of angle ABC 6

5

1

BA

,,,,,,,,,,,,,,4

0

6

BC

,,,,,,,,,,,,,,Vectors to point

away from vertex . 24 0 6 18BA BC ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

36 25 1 62BA ,,,,,,,,,,,,,,

16 36 52BC ,,,,,,,,,,,,,,

18cos

62 52 71.5

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A cuboid measuring 11cm by 5 cm by 7 cm is placed centrally on top of another cuboid measuring 17 cm by 9 cm by 8 cm.

Co-ordinate axes are taken as shown.

a) The point A has co-ordinates (0, 9, 8) and C has

co-ordinates (17, 0, 8).

Write down the co-ordinates of B

b) Calculate the size of angle ABC. (3, 2, 15)Ba) b)

3

7

7

BA

,,,,,,,,,,,,,,15

2

7

BC

,,,,,,,,,,,,,,

. 45 14 49 10BA BC ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

225 4 49 278BC ,,,,,,,,,,,,,,

9 49 49 107BA ,,,,,,,,,,,,,, 10

cos278 107

93.3

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A triangle ABC has vertices A(2, –1, 3), B(3, 6, 5) and C(6, 6, –2).

a) Find and

b) Calculate the size of angle BAC.

c) Hence find the area of the triangle.

AB,,,,,,,,,,,,,,

AC,,,,,,,,,,,,,,

1

7

2

AB

,,,,,,,,,,,,,,b aa)

4

7

5

AC

,,,,,,,,,,,,,,c a

b) 2 2 21 7 2 54AB ,,,,,,,,,,,,,,

90AC ,,,,,,,,,,,,,,

. 4 49 10 43AB AC ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

43cos 0.6168

54 90 1cos 0.6168 51.9 51.9 BAC =

c) Area of ABC = 1

2sinab C

190 54

2sin 51.9 2

unit27.43

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