Square area 81 m², find the side

Step by step

The question

Question: find the side s of a square with area 81 m².

1 Write the rule

All four sides of a square are the same.

The area is side times side.

So s times s is 81: s² = 81.

Careful!

Dividing by 4 is for the perimeter.

For the area we need the number that times itself makes it.

2 Take the square root

s times s is 81.

So s is the square root of 81.

The square root of 81 is the positive number that times itself makes 81.

9 times 9 is 81.

So the side is 9 m.

3 Check

Let's check: side times side.

We get 81, the area.

So the side is right!

Let's look back.

First: write the rule.

Then: take the square root.

Last: check.