Calculate Perimeter: Equilateral Triangle with 7-Unit Sides

To solve this problem, we'll follow these steps:

• Step 1: Recognize the triangle is equilateral with all sides having the same length.
• Step 2: Apply the perimeter formula for an equilateral triangle.
• Step 3: Calculate the perimeter using the provided side length.

Now, let's work through each step:
Step 1: We are given an equilateral triangle with one side length $7$. All sides in an equilateral triangle are the same, so each side is $7$.

Step 2: The formula for the perimeter $P$ of an equilateral triangle is given by:
$P = 3s$ where $s$ is the side length of the triangle.

Step 3: Plugging our known side length $s = 7$ into the formula, we have:
$P = 3 \times 7 = 21$

Therefore, the solution to the problem is 21.