SIFT Math Practice Test

To find the length of one side of a square when the perimeter is known, you can use the formula for the perimeter of a square. The perimeter \( P \) of a square is calculated as \( P = 4s \), where \( s \) is the length of one side.

In this case, you have the perimeter given as 36 cm. Setting up the equation based on the formula:

\[ 4s = 36 \]

To isolate \( s \), divide both sides of the equation by 4:

\[ s = \frac{36}{4} \]

Calculating this gives:

\[ s = 9 \text{ cm} \]

Thus, the length of one side of the square is indeed 9 cm, confirming that the correct answer is this option.