Find the area inside both r=5sin(2theta) and r=5cos(2theta).

I have NO idea how to do it. My book has no examples and I couldn't find anything online.

I ended up trying to do the integral of (5sin(2theta))^2, evaluated from 0 to Pi/8 + the integral of (5cos(2theta))^2 evaluated from 0 to Pi/8 and then multiplying the whole thing by 8 because of symmetry. I don't believe that to be correct.

Any explanations would be great!