Calculate ED Length When ED = 1/3 AB in Rectangle with Area 45

Question

The area of the rectangle below is equal to 45.

$ED=\frac{1}{3}AB$

Calculate the size of ED.

00:09 Let's find the length of ED.

00:12 To find the rectangle's area: multiply the length, AC, by the width, AB.

00:19 Now, let's plug in the values and solve for AB.

00:29 We're told that ED is one-third of AB.

00:33 And that's how we solve this problem!

The area of rectangle ABCD equals length times width.

Let's write down the known data in a formula to find side CD:

$45=5\times CD$

Let's divide both sides by 5:

$CD=9$

We know that in a rectangle, each pair of opposite sides are equal, therefore:

$AB=CD=9$

Since we are given that ED equals one-third of CD, we can substitute the known data and calculate side ED:

Remember that AB equals CD

$ED=\frac{1}{3}AB=\frac{1}{3}\times9=3$