A right cone has a slant height of 7 and a radius of 5. What is its surface area?

1 Answer
Feb 22, 2016

A surface area of a cone is the lateral area plus the area of the base

The lateral area of a cone is #pi r l#

The base area of a cone is #pir^2#

Therefore, the total surface area is #pi r l + pir^2#

We are given both variables l and r, so we just have to plug in

#SA = pi (5) (7) + pi(5)^2#

#SA = 35pi + 25pi#

#SA = 60pi#

The surface area is approximately 188.5