Question

The lateral area of a cone is 400 pi cm squared. The radius is 10 cm. Find the slant height to the nearest tenth.

A. 40 cm

B. 38.7 cm

C. 34 cm

D. 29.1 cm
THE ANSWER WAS A

Answer 1

Option A.
`40\ cm`

Explanation:

we know that

The lateral area of a cone is equal to

`LA=\pi rl`

we have

`LA=400\pi \ cm^(2)`

`r=10\ cm`

substitute and solve for l (slant height)

`400\pi=\pi (10)l`

simplify

`400=(10)l`

`l=400/10=40\ cm`