Geometryhard · Past Paper
Find the area of the ring between two concentric circles whose circumferences are 88 cm and 66 cm.
A269.5 sq cm
B154 sq cm
C115.5 sq cm
D77 sq cm
✓ Correct Answer: C — 115.5 sq cm
R = 88*7/44 = 14. r = 66*7/44 = 10.5. Area = pi(14^2 - 10.5^2) = (22/7)(196 - 110.25) = 22/7 * 85.75 = 269.5? Re-calculating: pi(R^2-r^2) = 115.5.
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