1. Splash Screen

2. Lesson Menu Five-Minute Check (over Lesson 11–2) Then/Now New Vocabulary Key Concept: Area of a Circle Example 1:Real-World Example: Area of a Circle Example 2:Use the Area of a Circle to Find a Missing Measure Key Concept: Area of a Sector Example 3:Real-World Example: Area of a Sector

3. Over Lesson 11–2 5-Minute Check 1 A.202 units 2 B.198 units 2 C.62.7 units 2 D.28.4 units 2 Find the area of the figure. Round to the nearest tenth if necessary.

4. Over Lesson 11–2 5-Minute Check 2 A.96 units 2 B.92.4 units 2 C.83.1 units 2 D.81.8 units 2 Find the area of the figure. Round to the nearest tenth if necessary.

5. Over Lesson 11–2 5-Minute Check 3 A.70 units 2 B.72.5 units 2 C.75 units 2 D.77.5 units 2 Find the area of the figure. Round to the nearest tenth if necessary.

6. Over Lesson 11–2 5-Minute Check 4 A.58.5 units 2 B.117 units 2 C.198 units 2 D.234 units 2 Find the area of the figure. Round to the nearest tenth if necessary.

7. Over Lesson 11–2 5-Minute Check 5 A.6 units B.5 units C.4 units D.3 units Trapezoid LMNO has an area of 55 square units. Find the height.

8. Over Lesson 11–2 5-Minute Check 6 A.4 m B.8 m C.16 m D.1800 m The area of a kite is 120 square meters. The length of one diagonal is 15 meters. Find the length of the other diagonal.

9. Then/Now You found the circumference of a circle. (Lesson 10–1) Find areas of circles. Find areas of sectors of circles.

10. Vocabulary sector of a circle segment of a circle

11. Concept 1

12. Example 1 Area of a Circle MANUFACTURING An outdoor accessories company manufactures circular covers for outdoor umbrellas. If the cover is 8 inches longer than the umbrella on each side, find the area of the cover in square inches. The diameter of the umbrella is 72 inches, and the cover must extend 8 inches in each direction. So, the diameter of the cover is 8 + 72 + 8 or 88 inches. Divide by 2 to find that the radius is 44 inches.

13. Example 1 Area of a Circle Answer:The area of the cover is about 6082 square inches. Area of a circle Substitution Use a calculator.

14. Example 1 A.62.8 ft 2 B.254.5 ft 2 C.314.2 ft 2 D.1256.6 ft 2 A swimming pool company manufactures circular covers for above ground pools. If the cover is 1 foot longer than the pool on each side, find the area of the cover.

15. Example 2 Use the Area of a Circle to Find a Missing Measure ALGEBRA Find the radius of a circle with an area of 58 square inches. Answer:The radius of the circle is about 4.3 in. Area of a circle Substitution Divide each side by . Simplify. 4.3 ≈ r Take the positive square root of each side. = r

16. Example 2 A.3.8 in. B.4.5 in. C.5.7 in. D.7.6 in. ALGEBRA Find the radius of a circle with an area of 45 square inches.

17. Concept 2

18. Example 3 Area of a Sector PIE A pie has a diameter of 9 inches and is cut into 10 congruent slices. What is the area of one slice to the nearest hundredth? Step 1Find the arc measure of a pie slice. Since the pie is equally divided into 10 slices, each slice will have an arc measure of 360 ÷ 10 or 36. Step 2Find the radius of the pie. Use this measure to find the area of the sector, or slice. The diameter is 9 inches, so the radius is 4.5 inches.

19. Example 3 Area of a Sector Area of a sector x = 36 and r = 4.5 Use a calculator. Answer:The area of one slice of pie is about 6.36 square inches.

20. Example 3 A.16.21 in 2 B.19.24 in 2 C.26.43 in 2 D.38.48 in 2 PIZZA A pizza has a diameter of 14 inches and is cut into 8 congruent slices. What is the area of one slice to the nearest hundredth?

21. End of the Lesson