The basic equation for a circle is:
(x – h)2 + (y – k)2 = r2
Where (h, k) is the point that locates the center of the circle and r is the radius.
If we locate the center at the origin of our coordinate axes:
x2 + y2 = r2
If we have a circle with origin of (4,0) and a 2 inch radius, write the equation for the circle.