Find the area of a shape enclosed between two circles with one center and radii of 3 and 15.

The desired figure is a ring, the inner radius of which is equal to the diameter of the smaller circle, ОА = 3 cm, and the outer radius of the larger circle ОВ = 15 cm.

The area of the figure is equal to the difference between the areas of the circles.

Determine the area of the larger circle. S1 = π * ОА ^ 2 = 9 * π cm2.

Let’s define the area of the smaller circle. S2 = π * ОВ ^ 2 = 225 * π cm2.

Then the area of the figure is: S = S2 – S1 = 225 * π – 9 * π = 216 * π cm2.

Answer: The area of the figure is 216 * π cm2.