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

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

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

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 = x360

πr2

r = 3 cm

120o

r = 6cm

60o

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

11.5 Area of Circles & Sectors

HW pg. 758 #3­31 odds 6

March 31, 2014

Annulus:region bounded by two concentric circles

11.5 Area of Circles & Sectors

HW pg. 758 #3­31 odds 7

March 31, 2014

R = 12cmr = 9 cm

r  

60o

R

The shaded area is 12π cm2.  Find r.

r

120o

11.5 Area of Circles & Sectors

HW pg. 758 #3­31 odds 8

March 31, 2014

11.5 HW pg. 758 #3-31 odds