1. Find the area of the figure. Round to the nearest tenth if necessary.
198 units2 A B C D
5-Minute Check 1

2. Find the area of the figure. Round to the nearest tenth if necessary.
83.1 units2 A B C D
5-Minute Check 2

3. Find the area of the figure. Round to the nearest tenth if necessary.
70 units2 A B C D
5-Minute Check 3

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

5. Find areas of sectors of circles.
In this lesson we will:
Find areas of circles.
Find areas of sectors of circles.
Then/Now

6. sector of a circle
segment of a circle
Vocabulary

7. Concept 1

8. 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 or 88 inches. Divide by 2 to find that the radius is 44 inches.
Example 1

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

10. 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 to the nearest tenth of an foot. A B C D
314.2 ft2
Example 1

11. Take the positive square root of each side. = r
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 to the nearest tenth of an inch.
Area of a circle
Substitution
Divide each side by .
Take the positive square root of each side.
= r
Simplify.
4.3 ≈ r
Answer: The radius of the circle is about 4.3 in.
Example 2

12. ALGEBRA Find the radius of a circle with an area of 45 square inches to the nearest tenth of an inch
Example 2

13. Concept 2

14. Step 1 Find the arc measure of a pie slice.
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 1 Find the arc measure of a pie slice.
Since the pie is equally divided into slices, each slice will have an arc measure of 360 ÷ 10 or 36.
Step 2 Find 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.
Example 3

15. Answer: The area of one slice of pie is about 6.36 square inches.
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 square inches.
Example 3

16. 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?
19.24 in2 A B C D
Example 3