1. The problem statement, all variables and given/known data A quarter disc of radius 3 cm lies in the first quadrant. The areal density is (1.2 g/cm3)x + (0.7 g/cm3)y. Determine the mass of this object. 2. Relevant equations 3. The attempt at a solution For my bounds: x: 0 to 3 y: 0 to Sqrt[3 - x^2] When I took this integral I got 2.07846 + 5.87878 I, which is obviously an imaginary number. Any idea how to get a real number? I'm not sure where I'm going wrong-- I thought this was simple calculus 2.