Question

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

Answer 1

Answer:

x² + y² = 225

Step-by-step explanation:

The equation of a circle centred at the origin is

x² + y² = r² ( where r is the radius )

here r = 15, hence

x² + y² = 15²

x² + y² = 225 ← equation of circle

Answer 2

Answer:

x^2 + y^2 = 225.

Step-by-step explanation:

The general form is x^2 + y^2 = r^2    where r = the radius of the circle.

The radius is 15 so the equation is x^2 + y^2 = 15^2.

That is x^2 + y^2 = 225.