Question

A right cone has a radius of 13 cm and an altitude of 52 cm. Find its surface area.

A. 2,668.7 cm2
B. 865.8 cm2
C. 849.5 cm2
D. 2,720.0 cm2

Answer 1

Option B.
`865.8\pi\ cm^(2)`

Explanation:

we know that

The surface area of the cone is equal to

`SA=\pi r^(2) +\pi rl`

we have

`r=13\ cm`

`h=52\ cm`

Find the slant height l

Applying Pythagoras \theorem

`l^(2)=r^(2) +h^(2)`

substitute the values

`l^(2)=13^(2) +52^(2)`

`l^(2)=2,873`

`l=53.6\ cm`

Find the surface area

`SA=\pi(13)^(2) +\pi(13)(53.6)=865.8\pi\ cm^(2)`