In this lesson we’ll look at how to write the equation of a circle in standard form in order to find the center and radius of the circle. The standard form for the equation of a circle is (x-h)^2+(y-k)^2=r^2, where r is the radius and (h,k) is the center. Sometimes in order to write the equation of a circle in standard form, you’ll need to complete the square twice, once for x and once for y.
Read MoreGiven the equation of a circle, we can put the equation in standard form, find the center and radius of the circle from the standard form, and then use the center and radius to graph the circle. Alternately, given the graph of the circle, we can identify the center and radius from the graph and then plug those values into the standard equation of the circle in order to get its equation.
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