Section 10.7. Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

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Section 10.7

description

 Two nonzero vectors u and v are orthogonal iff their dot product is zero.

Transcript of Section 10.7. Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Page 1: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Section 10.7

Page 2: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Multiply like components together, then addu1v1 + u2v2

Length of a vector:

Angle between Vectors Theorem:

uuu ||||

)|||| ||||

(cos 1

vuvu

Page 3: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Two nonzero vectors u and v are orthogonal iff their dot product is zero.

Page 4: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

A passenger jet is cruising at a speed of 300 knots in a direction 25˚ east of south and there is a 40 knot wind coming from the southwest. By how many degrees will the jet be thrown off course?

Jet’s velocity vector: [300, 295] Wind velocity vector: [40, 45]

Component: 300cos295 + 40 cos 45 300 sin 295 + 40 sin 45

Page 5: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Component: 300cos295 + 40 cos 45 300 sin 295 + 40 sin 45

(155.0697, -243.608)

Put back in polar form:

R = 288.776θ = -57.5˚

So the plane is getting “pushed” 7.48˚ off course.

Page 6: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Calculate the dot product of <-1, 8> and <-5, -10.2>

-1 * -5 + 8* -10.25 – 81.6

-76.6

Page 7: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Find the measure of the angle between the vectors u = <-9, 12> and v = <-4, 3>

Formula: )|||| ||||

(cos 1

vuvu

)5*15

72(cos 1 3.16

Page 8: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Explain the relationship between the dot product of two vectors and the angle between them.

If the dot product is positive, the angle is acute

If the dot product is negative, the angle is obtuse

If the dot product is zero, the angle is right.

Page 9: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Describe all vectors in the plane that are orthogonal to <17,5> and have length 4.

Two equations: 0 = 17v1 + 5v2

16 = v12 + v2

2

Solve for v2 in the first: v2 = -17/5 v1

Substitute back in: 16 = v12 + (-17/5v1)2

16 = v12 + (289/25)v1

2 16 = 314/25v1

2

400/314 = v12

131420

v 131420

v

Page 10: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

Two equations: 0 = 17v1 + 5v2

16 = v12 + v2

2

Solve for v2 in the first: v2 = -17/5 v1

Plug back in:

231420

517

v

231468

v

231420

517

v

231468

v

Page 11: Section 10.7.  Multiply like components together, then add u 1 v 1 + u 2 v 2 Length of a vector:…

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