The circumference of a circle varies directly as the radius. A circle with radius 3 in. has circumference 18.84 in. Find the circumference of the circle if the radius changes to 15 in.

Two-dimensional figure measured in terms of radius. It is formed by a set of points that are at a constant or fixed distance from a fixed point in the center of the plane. The parts of the circle are circumference, radius, diameter, chord, tangent, secant, arc of a circle, and segment in a circle.