This document provides examples of finding the center and radius of circles from their equations. It shows that if a circle equation is given as x^2 + y^2 + 2gx + 2fy + c = 0, then the center is (-g, -f) and the radius is the square root of g^2 + f^2 - c. It works through multiple examples, equating coefficients to find g, f, and c, and then uses this formula to determine the center and radius.