Question

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

Answer 1

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.

Answer 2

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.