Practice!

Sample Problem

If the volume of the cone is 180 in3, what is its surface area? Use 3.14 for π and round the answer to the nearest hundredth.

The surface area = in2.

Solution

V = 1/3 × πr2 × h

h = (3 × V) / (π × r2) = (3 × 180) / (3.14 × 25) = 6.88 in

l =  = 8.50 in

So, SA = πr2 + πrl

= 3.14 × 25 + 3.14 × 5 × 8.50

= 211.95 in2