Question

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

Answer 1

Answer:

x² + y² = 15² = 225

Step-by-step 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

Answer 2

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

$x^2+y^2=225$