- #1
Emspak
- 243
- 1
Homework Statement
This is a more general question, but I want to be sure I understand something here.
Take any function f(x,y) and say you're doing a double integral, like this:
[tex]\int^{\pi}_{\pi/2}\int^{sinx}_{\pi/2}f(x,y)dydx[/tex]
So I want to reverse the order of integration. The x-coordinate interval is π/2 to π, and the y-interval is 0 to sinx.
So that means that x=arcsin y. and the interval in those terms starts at 1. Am I correct so far?
If I switch the order of integration I have to put the y interval on the outside. But since the y interval is in terms of x I have to change that. On this curve y is between 0 and 1. So I should make the outer integral from 1 to 0 since we were originally starting at π/2.
The inner integral is therefore π/2 to arcsin y.
And when you re-order the integral you should get
[tex]\int^{1}_{0}\int^{sin^{-1}}_{\pi/2}f(x,y)dxdy[/tex]
But I know this is wrong and I am trying to make sure I understand why that is.
Any assistance is appreciated, as always.