Question #N24
A circle with center (2, 4) and radius 3 is graphed in the xy-plane. What is the equation of this circle?
A. (x - 2)^2 + (y - 4)^2 = 3
B. (x + 2)^2 + (y + 4)^2 = 9
C. (x - 2)^2 + (y - 4)^2 = 9
D. (x + 2)^2 + (y + 4)^2 = 3
Correct Answer is: C
The standard form of the equation of a circle is (x - h)^2 + (y - k)^2 = r^2, where (h, k) is the center of the circle and r is the radius. Since the center of the circle is (2, 4) and the radius is 3, the equation of the circle is (x - 2)^2 + (y - 4)^2 = 3^2, or (x - 2)^2 + (y - 4)^2 = 9.