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

2. © A Very Good Teacher 2008 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 =200 25 x = 8 gallons 8x =400 88 x = 50 hours

3. © A Very Good Teacher 2008 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

4. © A Very Good Teacher 2008 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 W 16 4 feet = Width

5. © A Very Good Teacher 2008 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

6. © A Very Good Teacher 2008 The Pythagorean Theorem Only works in RIGHT TRIANGLES! Parts of a Right Triangle: Obj. 3: 8.7C Right Angle Legs Hypotenuse a 2 + b 2 = c 2 a b c OR

7. © A Very Good Teacher 2008 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

8. © A Very Good Teacher 2008 The Coordinate Plane Parts of the Coordinate Plane Obj. 3: 8.7D x-axis y-axis Quadrant IQuadrant II Quadrant IIIQuadrant IV origin

9. © A Very Good Teacher 2008 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) (-4, 5) (4, -6)

10. © A Very Good Teacher 2008 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)

11. © A Very Good Teacher 2008 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 a 2 + b 2 = c 2