2. Transparency 3 Click the mouse button or press the Space Bar to display the answers.

3. Splash Screen

4. Example 3-1a Objective Find the areas of circles

5. Example 3-1a Vocabulary Circumference The distance around a circle

6. Example 3-1a Symbols Pi Approximately 3.14 You are to use the  key on the calculator

7. Lesson 3 Contents Example 1Find Areas of Circles Example 2Find Area of Circles Example 3Use Area to Solve a Problem

8. Example 3-1a Find the area of the circle to the nearest hundredth 1/3 Draw the circle and label the radius Write formula for area of circle Replace r with 5 yd A =   (5 yd) 2

9. Example 3-1a Find the area of the circle to the nearest hundredth 1/3 A =   (5 yd) 2 Find square of 5 yd A =   25 yd 2 Multiply by  A = 78.54 yd 2 Answer: Follow Order of Operations P E MD AS Must do exponents before multiplying

10. Example 3-1b Answer: 50.27 cm 2 Find the area of the circle to the nearest hundredth 1/3

11. Example 3-2a Find the area of the circle to the nearest hundredth 2/3 Draw the circle and label the diameter Remember: Diameter goes all the way across the circle and twice the radius Write formula for area of circle

12. Example 3-2a Find the area of the circle to the nearest hundredth 2/3 Since diameter is given must divide the diameter by 2 to find radius 10.8  2 = 5.4 Replace r with 5.4 in A =   (5.4 in) 2

13. Example 3-2a Find the area of the circle to the nearest hundredth 2/3 A =   (5.4 in) 2 Follow Order of Operations P E MD AS Must do exponents before multiplying Find square of 5.4 in A =   29.18 in 2 Multiply by  A = 91.61 in 2 Answer:

14. Example 3-2b Answer: 124.69 m 2 Find the area of the circle to the nearest hundredth 2/3

15. Example 3-3a CRATERS The Chicxulub Crater in the Yucatan Peninsula, Mexico, was caused by a crashing asteroid or comet about 65 million years ago. If the diameter measures 300 kilometers, what is the area covered by the crater? 3/3 Draw the circle and label the diameter 300 km Remember: Diameter goes all the way across the circle and twice the radius Write formula for area of circle

16. Example 3-3a 3/3 300 km Since diameter is given must divide the diameter by 2 to find radius 300  2 = 150 Replace r with 150 km A =   (150 km) 2

17. Example 3-3a 3/3 300 km A =   (150 km) 2 Follow Order of Operations P E MD AS Must do exponents before multiplying Find square of 150 km A =   22,500 km 2 Multiply by  A = 70,685.83 km 2 Answer:

18. Example 3-3b Answer: 452.39 ft 2 SWIMMING POOL A new children’s circular swimming pool being built at a local recreation center has a diameter of 24 feet. How much area does the new pool cover? 3/3

19. End of Lesson 3 Assignment Lesson 14:3Area of Circles4 - 16 All