Thursday, June 13, 2013

Finding the Perimeter of an Equilateral Triangle

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