Completing the Square

Completing the Square in Circle Equation

Circle of equation : (x – h)2 + (y – k)2 = r2

Center point :  (h,k)

Radius: r

To find the standard form of the given circle equation by factoring we can use a technique called completing the square. This will help us to quickly identify the circle’s center point (h,k) and the radius.

(Please click on the picture to see it clear)

Center Point and Radius

Keep in mind that the factored form of a circle equation reveals the center point (h,k) and the radius. In the above example, (3, -4) is the center point and the radius is the square root of 26.

Math Formulars

When it’s come to a point that WE all need to know these math formulas. It is not required to be memorized but it better to get a sense of how to calculate them.