math
posted by Ted on .
how do you calculate the surface area of a cone with a slant height of 13cm and a height of 12cm.?

To calculate the curved surface area of the cone, we need to know the base radius R.
The slant height (L) of a cone is 13 cm
The vertical height (H) is 12 cm
Use Pythagoras theorem to find the radius of the base, R
R² = L²  H²
R = sqrt(13²12²)
=5
The curved surface area of a cone is the product πRL = π*5*13 = 65π
To this, we should add the surface area of the base, equal to πR².