A circle has the equation x2 + y2 = 9. What is the length of the radius?

3

Step-by-step explanation:

The standard form of the equation of a circle is

(x - a) ^2 + (y - b) 2 = r ^2

where (a, b) are the coords of the centre and r, the radius.

x ^2 + y ^2 = 9

is in this form with a = b = 0 and r = 3

The center is (0,0) and the radius is 3

Step-by-step explanation:

The equation of a circle is given by

(x-h) ^2 + (y-k) ^2 = r^2

Where (h, k) is the center and r is the radius

(x-0) ^2 + (y-0) ^2 = 3^2

The center is (0,0) and the radius is 3