Question

What is the radius of the following circle?

x^2+y^2=15

Answer 1

it might help to recall the general equation of a circle, then its just a matter of comparing parts

Answer 2

Whats the equation??

Answer 3

it should be in your study material, if not, its posted online in about infinity+1 places ...

as a memory device, it is pythagorean

Answer 4

The general equation is
\[x^2+y^2=r^2\]
r is the radius,
Then you can see that
\[r^2=15\]
Then
\[r=?\]