1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution As with my other recent posts, I just want to check if I'm right or wrong as I don't have an answer scheme to go by. For this question I simply converted to polar to get: ∫∫(a+a)r drdθ for 0<r<a, 0<θ<2π , which solved to give 2πa3 . Was that correct? I'm convinced I did something wrong because it seems a very easy 7 marks. Thanks!