Example 3

Write the standard equation and the general equation of the circle that has center and passes through .
  1. Sketch the circle.
  2. Use the distance formula to find the radius, .
  3. Substitute the center and radius directly into the standard form.
  4. Square the binomials and rearrange terms to obtain the general form.
This applet is provided by Walch Education as supplemental material for their mathematics programs. Visit www.walch.com for more information.