Question

Given: The slant height of the cone is 18 mm.5 mm18 mmWhich is the surface area of the cone?O 907O 1007O 111.57O 1157

Answer 1

Given:

Radius of cone, r=5mm.

Slant height of the cone, l=18mm.

The Surface area of cone formula is,

$A=\pi rl$

Therefore, the surface area of the given cone is,

$\begin{gathered} A=\pi\times5\times18 \\ =90\pi \end{gathered}$

Therefore, the surface area of the given cone is,

$90\pi$

Hence, the lateral surface area of the cone ,

$90\pi$

The total surface area of the cone formula is,

$A=\pi r(l+r)$

Therefore,

$\begin{gathered} A=\pi(5)(5+18)_{} \\ =\pi\times5\times23 \\ =115\pi \end{gathered}$

Therefore, the correct option is D.