Question

Write a formula to find the length l of the rectangle.

Short answer

The formula for the length is:

$l=\frac{P-2w}{2}$

Step-by-step solution

Step 1. Given information.

The perimeter of the rectangle is P and w be the width of the rectangle.

Step 2. Concept used.

The perimeter of a rectangle is given by the following formula:

$P=2\left(l+w\right)$

Here l and w be the length and width of the rectangle respectively.

Step 3. Determine the formula.

Since,

$P=2\left(l+w\right)$

Then,

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

The above equation can write as:

$l=\frac{P-2w}{2}$

Step 4. Conclusion.

The formula to find the length of a rectangle is:

$l=\frac{P-2w}{2}$

Here l is the length, P is the perimeter and w is the width of the rectangle.