Rectangle Area Problem: Finding Side Length AB When Area = 63 and AC = 7

Question

The area of the rectangle below is equal to 63.

AC = 7

How long is side AB?

00:00 Determine the value of AB

00:03 The formula for calculating the area of a rectangle is width(AB) multiplied by length(AC)

00:07 Substitute the relevant values into the formula according to the given data and proceed to solve for AB

00:11 This is the solution

We use the formula to calculate a rectangle: length times width:

$AB\times AC=S$

We place the existing data into the formula:

$AB\times7=63$

$7AB=63$

We divide both sides by 7:

$AB=9$