Question

What is the radius for a circle whose equation is x^2+y^2=64

Answer 1

Answer:

8 is the radius.

Step-by-step explanation:

The standard form of a circle is $(x-h)^2+(y-k)^2=r^2$.

However, I like to call it center-radius form because it tells us the center and the radius.

The center is $(h,k)$ and the radius is $r$.

So your equation is $(x-0)^2+(y-0)^2=8^2$.

So the center for this circle is (0,0) and the radius is 8.

If it wasn't so obvious that $8^2$ is 64 then you could have entered $\sqrt{64}$ in your calculator to get 8.