Radius and center of a circle

Question

A circle is graphed on a coordinate system. The center is at the origin, and the point (0,3) lies on the circle.

You want to prove it disapprove that the point (1 and the square root of 8) lies on the circle

What is the radius of the circle?

What is the distance from the center to (1 square root of 8)

Does the point (1, square root of 8) lie on the circle?

Answer 1

If the center is (0,0) and the point (0,3) lies on the circle, then radius must be 3 and the equation of this circle is x² + y² = 9. You should be able to answer the rest of the questions with this information.