1. The problem statement, all variables and given/known data 2. Relevant equations Well i know the double integral formula for the joint pdf 3. The attempt at a solution So firstly we're told to find the joint pdf of X and Y. I'm not sure where to begin. So how do we find the function that we take the double integral over? I'm suspecting 1/2*b*h will be used and I know the joint pdf must equal 1, so do we equate this somehow to the formula for the area of a triangle? Could someone just point me in the right direction please? I suspect my bounds will be 0->1 and 0->x right? Or instead of the second one, 0->1-x ? Thanks in advance!