If the length of radius of a right circular cone be `(r)/(2)` unit and its slant height be `2l` unit , the total surface area of if will be

Options

A. `2pi r(l+r)` sq- unit
B. `pir(1+(r)/(4))` sq-unit
C. `pir(l+r)` sq-unit
D. `2pi`rl sq-unit

Explanation

The radius of the right circular cone is `(r)/(2)`, slant height `=2l` unit
`therefore` the total surface area of the cone `=pixx(pi)/(2)((r)/(2)+2l)"sq-unit"=pixx(r)/(2)xx2((r)/(4)+l)"sq-unit"`
`=pi r (l+(r)/(4))"sq-unit"`.
`therefore` (b) is correct.