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Areas of Circles & Sectors. Thm 11.7 – Area of a Circle –. A = r 2 * Remember to square the radius 1 st , then multiply by !. Ex : Find the area of circle C. A = r 2 A = (3) 2 A = 9 cm 2 OR 28.27 cm 2. 3 cm. C. Ex : Find the diameter of circle C if the area is 16 ft 2.
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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 3 cm C
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.
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. II R 50 cm L 150o M I
Ex: Find the area of the shaded region. r2 4 cm (4)2 16 16 - 12ð3 4 cm 2 30o = 29.5 cm2 2ð3 4ð3