Question

A cone with a radius of 3" has a total area of 24π sq. in. Find the volume of the cone.

Answer 1

The answer is 12π.

To get the volume of the cone, we need the height. The radius is given.

V = πr² × (h/3)

The total surface area of the cone is:
SA = πr² + πrl where r is radius and l is slant height

24π = π(3)² + π(3)(l)
24π = 9π + 3πl
24π - 9π = 3πl
15π = 3πl
l = 15π / 3π
l = 5

Using Phytagoras, we can calculate the height of the cone:
l² = h² + r²
5² = h² + 3²
25 - 9 = h²
h = √16
h = 4

Therefore the volume is:
V = π(3)² × (4 / 3)
V = 3π × 4
V = 12π

Answer 2

The volume of the cone is: 12 pi