Question

Given the circle: 3x2 + 3y2 – 12 = 36. Find its center and radius. A. (3,3) and r = 16 B. (0,0) and r = 16 C. (0,0) and r = 48 D. (0,0) and r=4

Answer 1

D. (0, 0) and r = 4.

Explanation:

3x2 + 3y2 – 12 = 36

3x^2 + 3y^2 = 48 Divide through by 3:

x^2 + y^2 = 16

Compare this with the formula:

(x - a)^2 + (y -b)^2 = r^2 where (a, b) is the centre and r = the radius.

So the centre is (0, 0) and radius = √16 = 4.