Answer to Question #140044 in Geometry for ZXC

Question

A silo has the form of a right circular cylinder 20m in diameter and 45m
high. The lateral surface of the silo is to be painted with two coats of
elastomeric paint.
1. What is the lateral surface area of the silo

Answer 1

Explanations & Calculations

• I guess what you find difficult in this question is the concept involved in this. Once its known this is an easy math.
• Before estimating the lateral surface, unfold the curved surface as shown.
• Now the $\small l$ is the circumference of the top face & the area (A) is the area of that rectangle.
• With that cleared,

$\qquad\qquad \begin{aligned} \small A &= \small l\times h\\ &= \small (\pi \times20m)\times 45m\\ &= \small \bold{2827.43m^2} \end{aligned}$