What is the radius of the circle given by the equation x^2+y^2=49?

A. 3

B. 5

C. 7

D. 49

The answer is "C. 7."

The equation of a circle is (x-h) ² + (y-k) ²=r². r² represents the radius squared, or multiplied by itself. 7 multiplied by 7 is equal to 49, so the radius of the circle would be 7.

Formula of the circle

(x-a) ² + (y-b) ² = r²,

where r is a radius, (a, b) - coordinates of the center.

So,

x² + y² = 49

(x-0) ² + (y-0) ² = 49.

Center of this circle has coordinates (0,0).

x² + y² = 7²

r = 7

Answer is C. 7.