Question

Which of the following is the equation of a circle whose center is at the origin and whose radius is 4?

A. x2 + y2 = 2
B. x2 + y2 = 4
C. x2 + y2 = 16

Answer 1

(x-h)^2+(y-k)^2=r^2
center is (h,k)
radius is r

given
(0,0)=center
radius=4

(x-0)^2+(y-0)^2=4^2
x^2+y^2=16
C

Answer 2

C. x^2 + y^2 = 16

Explanation

The standard form: (x - h)^2 + (y-k)^2 = r^2, where (h, k) is the center and r is the radius of the circle.

Given: (h, k) = (0, 0) and r = 4.

Now plug in the given values in the standard form, we get

(x - 0)^2 + (y - 0)^2 = 4^2

x^2 + y^2 = 16

The answer is C. x^2 + y^2 = 16

Hope this will helpful.

Thank you.