How do you find the center and radius of x2 Y2 16?

Answer 1

You need to think of that equation in terms of the classic definition of a circle:

(x - a)2 + (y - b)2 = r2

where a and b are the center of the circle, x and y are any point on it's circumference, and r is it's radius.

In the case of the circle you're looking at:

x2 + y2 = 16

You can re-express it like this:

(x - 0)2 + (y - 0)2 = 42

So that circle has a center at the point (0, 0), and a radius of 4.