Given a soda can with a volume of 21 and a diameter of 6, what is the volume of a cone that fits perfectly inside the soda can?

Volume of a can:

21 = r² π h

21 = 3² π h

21 = 9 π h

h = 21 / 9π = 7 / 3π

Volume of a cone that fits perfectly inside a can:

V = 1/3 r² π h = 1/3 · 9 π · 7 / 3π = 7

Or you can use: V cone = 1/3 V cylinder (with the same basis)

V cone = 1/3 * 21 = 7