Geometry
10.7 Areas of Circles and Sectors
A. Area of a Circle: the area of a circle is the product of π and the square of the radius
Areacircle = πr2
B. Examples. Find the area of the following.
1.
3.
2. 6 cm
19 in
9 m
Mar 15­3:04 PM
1
C. Find the missing measurement 4. Find the radius and circumference of a circle with an area of 49π m2 .
5. What is the diameter and circumference of a circle with an area of 36π yds2?
6. Find the circumference and diameter of a circle with an area of 144π m2 ?
* A = 78.5 cm2. Find the radius and circumference.
Mar 15­3:06 PM
2
D. Sectors: the sector of a circle is the region bounded by an arc of the circle and the two radii to the arc’s endpoints
Mar 15­3:07 PM
3
E. Examples. Find the area of each sector
8. 7. 9. 1100
3 yd
10 ft
500
9 cm
900
Mar 15­3:08 PM
4
F. Segment of a circle ‐ a segment of a circle is the part bounded by an arc and the segment joining the endpoints
Examples: Find the area of each segment of a circle
10. 11. 11 in
1200
600
24 ft
Mar 15­3:11 PM
5
10.7 HW p. 577 #s 1 ­ 6, 8 ­ 12 even, 13, 14, 17 ­ 20, 22, 25 ­ 27, 41 ­ 46
Mar 23­11:40 AM
6