4. Find the equation of the circle centered at (2, 3) of radius 5.

We use the equation of the circle

(x - xo)2 + (y - y o)2 = r2

In this case

(xo, yo) = (2, 3)

and

r = 5

so the equation becomes

(x - 2) )2 + (y - 3 )2 = 25