Question

Find the missing side and then find the perimeter.

Answer 1

The missing side is 7.2 mi, and the perimeter is 22.4 mi.

Explanation:

The formula for a rectangle is length · width = area.

Replacing the known values in the equation makes it; 4 × width = 28.8

Dividing both sides by 4 makes it; width = 7.2

The formula for the perimeter of a rectangle is (2 × length) + (2 × width).

Replacing all known values changes the expression to; (2 × 7.2) + (2 × 4).

This simplified equals; 14.4 + 8, which is just 22.4.

Answer 2

Take the formula for the area of a rectangle:

A=L•W

We have “A” (area) and “W” (width) already, so we need to solve for “L” (length). From the figure, we are given that the are is 28.8 mi² and the width is 4 mi. So, let’s plug those values into the formula and solve for “L” (length).

(28.8mi²)=L•(4mi)

We simply input the equal values into the formula.

Solve for “L:”

Divide both sides by 4:

28.8/4=4•L/4

Simplify:

7.2=L

L=7.2

Therefore, the length is 7.2 mi