Finding the perimeter of an equilateral triangle

First, an equilateral triangle is a triangle that has three equal sides. In order to find the perimeter you can add the three sides together or you can just three times the length of one side.

**Video Perimeter of an Equilateral Triangle**

**Problem 1.** Find the perimeter of an equilateral triangle with a side of twelve units.

Step 1. 3*12 = 36 units

**Problem 2.** Find the perimeter of an equilateral triangle with an altitude of 12 units.

**Step 1**. Find the length of one side. The altitude creates a 30-60-90 triangle. The altitude becomes the long side of a 30-60-90 triangle.

**Step 2**. In order to get the side length use (long side of 30-60-90 triangle)/√3 which equals 12/√3

For a review of 30-60-90 rules check here

**Step 3.** 12/√3 = 4√3 which is the length of half of the equilateral side length

**Step 4.** In order to get the entire length take 2* 4√3 =

**Step 5.** Now you can use 3 * the side length or 3* 8√3= 24√(3 ) units