# Change of variables

1. Nov 10, 2008

1. The problem statement, all variables and given/known data
Make the appropriate change of variables and evaluate $$\int\int _R\(sin(9x^2+4y^2)}\;dA$$

2. Relevant equations

R is bounded by the ellipse $$9x^2+4y^2=1$$

3. The attempt at a solution

I can't figure out what the substitution should be I tried u=9x^2 and v=4y^2 and that didn't work and I don't know where to go from here.

2. Nov 10, 2008

### Dick

How about u=3x and v=2y? Then switch to polar coordinates in u and v.

3. Nov 10, 2008