Question

What is the surface area of the right cone below? Thanks!!

Answer 1

$A=\pi r(r+l)\\r=4\\l=13\\\\A=\pi \cdot 4(4+13)=4\pi \cdot 17=68\pi$

Answer 2

Hello!

The answer is:

The correct option is D.

$SurfaceArea=68\pi units^{2}$

Why?

To find the surface area of the right cone, we need to use the following formula:

$SurfaceArea=\pi rl+\pi r^{2}$

From the picture we have that:

$slant=l=13units\\radius=r=4units$

So, substituting and calculating we have:

$SurfaceArea=\pi rl+\pi r^{2}$

$SurfaceArea=\pi *4*13+\pi *4^{2}\\\\SurfaceArea=52\pi units^{2}+16\pi units^{2}=68\pi units^{2}$

Hence, the correct option is D.

Have a nice day!