Question

The formula for the total surface area of a cone is ___________.

Answer 1

Let $r$ be radius of a circular surface and $s$ be the length of a side of cone.

Area of the base $=$ Area of circular part $=\pi r^2$

And area of curved surface $=\pi rs$

Now, total surface area of a cone $=$ Area of a base $+$ Area of curved surface

$=\pi r+\pi rs$

$=\pi r(r+s)$