1. The problem statement, all variables and given/known data Find the dimensions of the rectangle of largest area that can be inscribed in a circle of radius r. 2. Relevant equations (x-a)^2 + (y-b)^2 = r^2 max area = 2x(2y) = 4xy 3. The attempt at a solution (x-a)^2 + (y-b)^2 = r^2 = y=r-(x-a)+b I then plug this into the max area = 4x(r-(x-a)+b) I know I need to differentiate, but I'm not sure how to go about this. I know I need to use the product rule, if its setup properly.