Question

What is the equation of a circle centered at the origin with radius 15​

Answer 1

The equation of a circle with center (h,k) and radius r is

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

In your case, (h,k)=(0,0) and r=15, so the equation becomes

`x^2+y^2=225`

Answer 2

x² + y² = 15² = 225

Explanation:

The equation of a circle of radius r centered at the origin is

x² + y² = r²

If the radius is 15, then the equation is x² + y² = 15² = 225