Formula: Right Circular Frustum Lateral area
$$A_{\text m} ~=~ \pi \, s \, \left( \class{red}{r_1} ~+~ \class{blue}{r_2} \right)$$
$$A_{\text m} ~=~ \pi \, s \, \left( \class{red}{r_1} ~+~ \class{blue}{r_2} \right)$$
$$s ~=~ \frac{ A_{\text m} }{ \pi \, \left( \class{red}{r_1} ~+~ \class{blue}{r_2} \right) }$$
$$\class{blue}{r_2} ~=~ \frac{ A_{\text m} }{ \pi \, s } - \class{red}{r_1}$$
$$\class{red}{r_1} ~=~ \frac{ A_{\text m} }{ \pi \, s } - \class{blue}{r_2}$$
Lateral area
$$ A_{\text m} $$ Unit $$ \mathrm{m}^2 $$
It is the area of the lateral surface of a right circular frustum. That means: The area of the top and base are not counted.
Side length
$$ s $$ Unit $$ \mathrm{m} $$
Side length of a right circular frustum (see illustration).
Radius of the base
$$ \class{red}{r_1} $$ Unit $$ \mathrm{m} $$
Radius of the lower circular plane.
Radius of the top
$$ \class{blue}{r_2} $$ Unit $$ \mathrm{m} $$
Radius of the upper circular plane.
Pi
$$ \pi $$ Unit $$ - $$
Pi is a mathematical constant and has the value \( \pi ~=~ 3.1415926... \)