two random variables have a join pdf
f(x,y)= c , x^2+y^2<= 1, x >0, y>0
The Attempt at a Solution
For the first part, since area= pi/4,
c(pi/4) = 1
y= sin θ
∫∫-(sin θ)^2(cos θ)^2 dθ dθ = -308. (integral from 0 to pi/2 for both bounds)
This doesn't make sense to me. x,y are always positive how is the expected value negative? Am I doing something wrong?