A rectangle has an area of 400 $\text{cm}^2$. If the rectangle is a square, what is its perimeter?
If $s$ is the side of the square, then $s^2=400$.  Therefore, $s=20$.  The perimeter is $4(20)=\boxed{80}$ cm.
80
Level 2
Prealgebra
Problem: A rectangle has an area of 400 $\text{cm}^2$. If the rectangle is a square, what is its perimeter?
Solution:<|START_OF_LATENT|><|PRIOR_PREFIX|>To find the perimeter of a square given its area, we first need to understand the relationship between the area and the side length of a square. The area \( A \) of a square is calculated using the formula \( A = s^2 \), where \( s \) is the length of one side of the square.

Given that the area of the rectangle (which is also a square in this case) is 400 cm², we can set up the equation:

s² = 400

To find the side length \( s \), we take the square root of both sides:

s = √400

Calculating the square root gives us:

s = 20 cm

Now that we have the side length, we can calculate the perimeter \( P \) of the square. The perimeter of a square is given by the formula:

P = 4s

Substituting the value of \( s \):

P = 4 × 20

Calculating this gives:

P = 80 cm

Thus, the final answer is 80.<|END_OF_LATENT|> The final answer is $80$.