Arc length (mostly a problem with integration)

[Geekchick]

Homework Statement

Find the arc length oh the graph f(x)=cosx on the integral [0,\frac{\pi}{2}]

Homework Equations

\int^{b}_{a}\sqrt{1+{f'(x)}^{2}}dx

The Attempt at a Solution

Alright so I took the derivative of f(x) to get f'(x)=-sinx then I squared it to get sin^{2}x so I could plug it into the formula to get \int^{\frac{\pi}{2}}_{0}\sqrt{1+sin^{2}x} the problem is when I try to integrate...well i can't. I tried to use substitution but since i don't have cos^{2}x anywhere I had some issues.

 

[Geekchick]

Anybody? Please this is driving me crazy!

 

[djeitnstine]

You can't do it. You have to do a numerical approximation

 

[djeitnstine]

I get 1.910098938245763 with wxmaxima