11.5 – areas of circles and sectors. area of a circle: a= r 2
TRANSCRIPT
11.5 – Areas of Circles and Sectors
Area of a Circle:
A= r2
Area of a Sector: Area between two radii in a circle
2
area of sector degree of arc
360r
1. Find the area of the circle.
A= r2
A= (7)2
A= 49cm2
1. Find the area of the circle.
A= r2
A= (6.5)2
A= 42.25in2
( )
2. Find the area of the shaded figure.
A = +
A = r2
2+ bh
A = (2)2
2+ (4)(4)
44
4
A = 4 2
+ 16
A = 2 + 16 ft2
( )
2. Find the area of the shaded figure.
A = –
8in
4in
r2A = –s2
(4)2A = –(8)2
16A = –64
16A = – 64 in2
8in
3. The area of a circle is 58 square inches. Find the diameter. Round to two decimal places.
A = r2
58 = r2
18.46 = r2
4.30in = r
d = 8.59in
4. Find the area of sector formed by ACB. Round to two decimal places. Leave answers in terms of pi.
2(10)
x
360x = 6000
216.67x in
2
area of sector degree of arc
360r
60
360
220
x
360x = 40000
x = 11.11m2
2
area of sector degree of arc
360r
100
360
5. Find the area of sector formed by PSQ. Round to two decimal places. Leave answers in terms of pi.
6. Find the area of sector formed by ACB. Round to two decimal places. Leave answers in terms of pi.
110
360
360x = 7040
219.56x in
110°
2
area of sector degree of arc
360r
2(8)
x
2(5)
x
360x = 7050
282°
2
area of sector degree of arc
360r
282
360
219.58x ft
7. Find the area of sector formed by PSQ. Round to two decimal places. Leave answers in terms of pi.