Find the surface area of a cone that has a slant height of 20 ft and the radius of the base is 10ft

Question

The cone has a slant height of 20ft and the crock base has a radius of 10ft (use pi=3.14) I basically need to find the height of the cone and then I'll be able to solve it

Answer 1

If you were calculating volume you would calculate the height knowing there was a triangle of hypotenuse slant height l and adjacent side radius? Here the slant height gives you a nice paramtwre for finding the side od the cone. Think of the side as a rectangle with a length being the circumference of the circular base (2pi *radius) and width being the slant height l. Then the area of the circle is PI *r^2. So SA is 2*3.14*r*l+ 3.14 * r^2.

 

Hope that helps,

Deanna