Do you really want to send doy a message saying you like their work?
Useful information about circles:
Standard Form: (x-h)²+(y-k)²=r² Eccentricity: e=0 Center: (h,k) Diameter: 2r Parametric Form: x′=rsin(t) or x′=rcos(t) y′=rcos(t) y′=rsin(t)