# geometry

Given a circle with the radius of 2, which is the degree measure of an arc whose length is 1/2 pi?

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1. arc-length = rß where ß is in radians
pi/2 = 2ß
ß= pi/4 radians, which is 45 degrees

or

the whole circumference would be 2(pi)r
= 4pi
now by a simple ratio ....
(1/2)pi/(4pi) = angle/360
4angle = 180
angle = 45

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posted by Reiny

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