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February 12, 2016
Posted by **Anonymous** on Wednesday, June 4, 2008 at 10:21pm.

I don't understand why the answer is pi/6. I get pi/3. Thanks for the help!

Work:

u=x/2 du=1/2dx 2du=dx

2/2sqrt(1-u^2)

sin^-1(x/2)

sin^-1(sqrt(3)/2)= pi/3

- Calculus -
**drwls**, Wednesday, June 4, 2008 at 10:54pmIntegral of dx/sqrt(4-x^2

Let x = 2u and that becomes

2 du/sqrt(4 - 4u^2)

Integral of du/(sqrt(1-u^2)

= sin^1 u = sin^-1(x/2)

OK so far.. sin-1(sqrt3/2) - sin^-1 0

= pi/3

I agree with your answer