Question

Given the formula for perimeter of a rectangle P=21+2w (where p is perimeter L is length and w is worth) which formula would you use to solve for length ?

Answer 1

Given the below formula for perimeter of a rectangle;

$P=2l+2w$

To make l(length) the subject of formula, we first of all need to subtract 2w from both sides of the equation;

$P-2w=2l$

The next step is to divide both sides of the equation by 2;

$\begin{gathered} l=\frac{P-2w}{2} \\ \therefore l=\frac{P}{2}-w \end{gathered}$

So, the formula for finding length is (l = P/2 - w).