© A Very Good Teacher 2008 8 th Grade TAKS Review 2008 Objective 3 Day 2.

© A Very Good Teacher 2008

8th Grade TAKS Review 2008

Objective 3

Day 2


Distance and Rates• If a car travels 25 miles on 1 gallon of gas, how

many gallons of gas will the car need to travel 200 miles?

• Michael earns $8 per hour. How many hours will he need to work to earn $400?

Obj. 3: 8.7B

25x = 20025 25

x = 8 gallons

8x = 4008 8

x = 50 hours


Area Problems• The amount of material needed to cover a

surface is the AREA of that figure.

• Example: Gary is tiling his dining room. The dimensions are shown below. What is the least amount of material needed to cover the floor?

Obj. 3: 8.7B

13 feet

18 feet

Area = Length x Width

Area = 18 x 13

Area = 234 square feet


Area Problems - Backwards• Example: A rectangle has an area of 64

square feet and a length of 16 feet. What is the width of the rectangle?

Obj. 3: 8.7B

Area = Length x Width

64 = 16 x W16 16

4 feet = Width


Rotations of Circles• When a wheel rolls 1 rotation it travels a

distance equal to the circumference of the circle.

• Example: The wheel shown has a radius of 4 inches. What distance is traveled by the wheel in 5 rotations?

Obj. 3: 8.7B

Distance = Circumference x Rotations

Distance = 2πr x 5

Distance = 2π4 x 5

Distance = 25.12 x 5

Distance = 125.6 inches


The Pythagorean Theorem• Only works in RIGHT TRIANGLES!

• Parts of a Right Triangle:

Obj. 3: 8.7C

Right Angle

Legs

Hypotenuse

a2 + b2 = c2

a

b

c

OR


The Pythagorean Theorem, cont…

• Example: Segment d is a diagonal in each of the shapes shown below. Which drawing shows enough information to find the length of segment d?

A. B.

C. D.

Obj. 3: 8.7C

4

4

d 4

8

d

4

6

d

4 4

d


The Coordinate Plane• Parts of the Coordinate Plane

Obj. 3: 8.7D

x-axis

y-axis

Quadrant IQuadrant II

Quadrant III Quadrant IV

origin


The Coordinate Plane, cont…• Graphing Points

(Ordered Pairs)• Start at the origin• (x, y)

x tells you how far to go left or right

y tells you how far to go up or down

• Examples:

Obj. 3: 8.7D

(6, 2)

(6, 2)

(-4, 5)

(-4, 5)

(4, -6)

(4, -6)


The Coordinate Plane, cont…• Example: Which of the following points lies

on the circle shown on the coordinate plane below?

Obj. 3: 8.7D

A. (1, 0)

B. (7, 6)

C. (-3, -4)

D. (-5, 6)

(1, 0)

(7, 6)

(-3, -4)

(-5, 6)


Vocabulary• Area – the amount of material needed to cover a surface

• Rotation – the spinning of an object (revolution)• Pythagorean Theorem

Legs – the sides that form the right angle Hypotenuse – The side across from the right angle Right Angle – an angle that measures 90°

• Coordinate Plane – grid used for graphing points X-axis – the horizontal line on the graph Y-axis – the vertical line on the graph Origin – the center of a graph Quadrants – the four areas created by the x and y-axis

a2 + b2 = c2

© A Very Good Teacher 2008 8 th Grade TAKS Review 2008 Objective 3 Day 2.

Documents

Transcript of © A Very Good Teacher 2008 8 th Grade TAKS Review 2008 Objective 3 Day 2.