1. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 1
March 31, 2014
Bellwork
about 56.5 cm.
8.64 cm
100.53 cm
7.64 ft

2. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 2
March 31, 2014
A circle has an area of ≈ 38.485 in2
.
What is the circumference of the circle?
11.5 Areas of Circles & Sectors
Area of Circle = πr2
(fuzzy wuzzy)
4.2 m

3. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 3
March 31, 2014
20 in
Find the area of the shaded region.
10 cm

4. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 4
March 31, 2014
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
360
πr2
r = 3 cm
120
o
r = 6cm
60
o

5. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 5
March 31, 2014
Segment of a Circle:
region bounded by a chord of a circle
& the included arc
r = 8 cm

6. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 6
March 31, 2014
Annulus:
region bounded by two concentric circles

7. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 7
March 31, 2014
R = 12cm
r = 9 cm
r
60o
R
The shaded area is 12π cm2.
Find r.
r
120o

8. 11.5 Area of Circles & Sectors
HW pg. 758 #3­31 odds 8
March 31, 2014
11.5 HW pg. 758 #3-31 odds