1. The problem statement, all variables and given/known data A thin wire has the shape of the first quadrant part of the circle with center at the origin and radius a. If the density function is rho(x,y)=kxy, find the mass and center of mass of the wire. 2. Relevant equations My parametric equation of the circle was x=a*cos(t) and y=a*sin(t). 3. The attempt at a solution I really have no clue where to begin for finding the center of mass of the wire. I think I got the mass via integral(k*a^2*sin(t)*cos(t) dt = -(k*a^2)/2. Thanks for the help!