The diagonal of a square is the hypotenuse of a 45-45-90 triangle.

In a 45-45-90 triangle the hypotenuse is the leg multiplied by `sqrt(2).`

Therefore, if given the hypotenuse, divide by `sqrt(2)` to find the length of the leg.

`sqrt(84)/sqrt(2) =sqrt(42)`

Therefore each side of the square is `sqrt(42).`

To find the...

## Unlock

This Answer NowStart your **48-hour free trial** to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Already a member? Log in here.

The diagonal of a square is the hypotenuse of a 45-45-90 triangle.

In a 45-45-90 triangle the hypotenuse is the leg multiplied by `sqrt(2).`

Therefore, if given the hypotenuse, divide by `sqrt(2)` to find the length of the leg.

`sqrt(84)/sqrt(2) =sqrt(42)`

Therefore each side of the square is `sqrt(42).`

To find the area of the square: `A=s^2.`

`A = (sqrt(42))^2`

**Therefore the area of the square is: `42 u^2` **

The length of the diagonal of a square with side S is equal to `sqrt(S^2 + S^2)` = `S*sqrt 2` .

If the diagonal of a square is D, the length of the side is `D/sqrt 2`

A square has a diagonal of length `sqrt 84` . The area of the square is `(sqrt 84)^2/2 = 84/2 = 42`

**The area of the square is 42 square units.**