Question

A cone has a perpendicular height of 12cm and slant height of 13cm . Calculate it's total surface area (take pie r =3.142)?

Answer 1

`282.78 cm^2`

Explanation:

For a cone, `l^2=r^2+h^2`, where, `l` is the slant height, `r` is radius and `h` is perpendicular height.

Given, `l=13cm,h=12cm`

So, `r=sqrt(13^2-12^2)=5cm`

Now, area of base of a cone is `pi r^2` and area of lateral surface is `pirl`

So,total area is `pi r^2 + pi rl`

i.e `pi r(r+l)=3.142×5×(5+13)=282.78 cm^2`