Areas of Circles & Sectors. Thm 11.7 – Area of a Circle – A = r2 * Remember to square the radius 1st, then multiply by !

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Areas of Circles & Sectors

Thm 11.7 – Area of a Circle – A = r2 * Remember to square the radius 1st, then multiply by !

Ex: Find the area of circle C. A = r2 A = (3)2 A = 9 cm2 OR 28.27 cm2 C 3 cm

Ex: Find the diameter of circle C if the area is 16 ft2. A = r2 16 = r2 16 = r2 ð16 = r 4 ft = r So, d = 8 ft.

Sector of a Circle The region bounded by 2 radii & their intercepted arc. Sector Also a sector Visually, it might remind you of a slice of pizza or a piece of pie.

Thm 10-12 – Area of a Sector –

Ex: Find the area of the small sector shown. 135o 1 1 m

Ex: L & M are 2 pts. on a circle R with r=50 cm & mLRM=150o. Find the areas of the sectors formed by LRM. 150o I II L M R 5 0 c m

Ex: Find the area of the shaded region. 4 c m r 2 4 c m 30o 2 2ð3 4ð3 (4) 2 16 16 - 12ð3 = 29.5 cm2

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