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Definite Integral (Posted on 2002-08-06) Difficulty: 3 of 5
Let f(x) = √(1-x²)

Find the definite integral of f(x) between x = 0 and x = 1

See The Solution Submitted by Cheradenine    
Rating: 3.0000 (8 votes)

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More Generally | Comment 13 of 15 |
The definite integral of f(x) between x=0 and x=t can be evaluated as

(1/2)[arcsin(t)+t*sqrt(1-t^2)]

using elementary integration techniques and trig identities. First making the substitution x=sin(u) changes the integral to that of [cos(u)]^2=(1/2)[1+cos(2u)] from u=0 to u=arcsin(t) from which the result follows readily upon using the double angle formula for the sine.

Setting t=1 then yields PI/4 as the answer to the original problem.

  Posted by Richard on 2006-08-26 13:17:33
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