What is the standard form of the equation of the given circle with center A (4, 8) ?

A.) (x - 4) ^2 + (y - 8) ^2 = 2.5

B.) (x + 4) ^2 + (y + 8) ^2 = 6.25

C.) (x + 4) ^2 + (y + 8) ^2 = 2.5

D.) (x - 4) ^2 + (y - 8) ^2 = 6.25

The standard equation of a circle is expressed as (x - h) ^2 + (y - k) ^2 = r^2 where (h, k) is the center of the circle and r is the radius of the circle. When center is at (4,8), then the left side should be (x - 4) ^2 + (y - 8) ^2. i guess the radius is 2.5 so that r^2 is equal to 6.25. Hence the answer is D