# Double Integrals Problem

• Oct 11th 2013, 08:04 PM
tastylick
Double Integrals Problem
This is the question and the integral i setup. But its wrong. Not sure where i went wrong.

Attachment 29448

This is the equation that I setup

$\int_0^\frac{\pi}{2} \int_0^\pi$ $sin(x)sin(y)dxdy$

I also tried setting x range $-\pi$ to $\pi$ but i kept getting zero.
• Oct 11th 2013, 11:50 PM
chiro
Re: Double Integrals Problem
Hey tastylick.

Hint: Your x limits should be from -pi to +pi (as you have suggested). Using this gives us

Integral [0,pi/2] sin(y)[-cos(pi) + cos(-pi)]dy
Integral [0,pi/2] sin(y)[-1-1]
Integral [0,pi/2[ -2*sin(y)
= 2[cos(pi/2) - cos(0)] = -2.