An annulus has a 36 centimeter chord of the outer circle that is also tangent to the inner concentric circle. What is the area of the annulus?
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Anonymous
ANSWERS: 1
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In the right angled triangle joining half the chord to the center, R^2 = 18^2 + r^2 by Pythagoras. and R^2 - r^2 = 18^2 Area of annulus = outer circle - inner circle = pi R^2 - pi r^2 = pi (R^2 - r^2) = 18^2 pi = 324 pi square centitmeters = approx 1018 square centimeters
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