1. 11.5 Area of Sectors March 21, 2013
Bellwork
8.64 cm
about 56.5 cm.
100.53 cm
7.64 ft
Mar 7­10:42 AM
HW pg. 758 #3­31 odds 1

2. 11.5 Area of Sectors March 21, 2013
11.5 Areas of Circles & Sectors
Area of Circle = πr2 (fuzzy wuzzy)
4.2 m
A circle has an area of 38.485 in2.
≈
What is the circumference of the circle?
Mar 7­10:43 AM
HW pg. 758 #3­31 odds 2

3. 11.5 Area of Sectors March 21, 2013
Find the area of the shaded region.
20 in
10 cm
Mar 7­10:46 AM
HW pg. 758 #3­31 odds 3

4. 11.5 Area of Sectors March 21, 2013
Sector of a Circle:
region bounded by 2 radii of a circle & the included arc
Formula for the Area of a Sector:
“portion of the circle times the area of the circle”
Asector = x πr2
360
o
120
r = 3 cm
o
60
r = 6cm
Mar 7­10:48 AM
HW pg. 758 #3­31 odds 4

5. 11.5 Area of Sectors March 21, 2013
Segment of a Circle:
region bounded by a chord of a circle
& the included arc
r = 8 cm
Mar 7­11:35 AM
HW pg. 758 #3­31 odds 5

6. 11.5 Area of Sectors March 21, 2013
Annulus:
region bounded by two concentric circles
Mar 7­11:38 AM
HW pg. 758 #3­31 odds 6

7. 11.5 Area of Sectors March 21, 2013
R = 12cm
r = 9 cm
R
r
60o
The shaded area is 12π cm2.
Find r.
120o
r
Mar 7­11:39 AM
HW pg. 758 #3­31 odds 7

8. 11.5 Area of Sectors March 21, 2013
11.5 HW pg. 758 #3-31 odds
Mar 7­11:41 AM
HW pg. 758 #3­31 odds 8