Question

The perimeter of a rectangular pentagon is $100\text{m}$. How long is its each side?

• A. $400\text{m}$
• B. $20\text{m}$
• C. $500\text{m}$
• D. $50\text{m}$

Answer 1

The correct option is B

$20\text{m}$

• The perimeter $P$ of a regular polygon with $n$ number of sides is given by,
• $P=n\times \text{length of each side}$.

Step 1: In the pentagon there are $5$ sides. Substitute $P=100$ and $n=5$ into $P=n\times \text{length of each side}$ and solve for the length of each side.

$100=5\times \text{length of each side}$

Step 2: Divide both sides of the equation by $5$ and solve for the length of each side.

$\begin{array}{rcl}\frac{100}{5}& =& \frac{5\times \text{length of each side}}{5}\\ \text{length of each side}& =& 20\text{m}\end{array}$

Hence, the length of each side is $20\text{m}$. So, the correct option is $\mathit{b}$.