How To Find The Perimeter Of A Regular/Equilateral Triangle ABC

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Calculating the perimeter of a regular triangle, also known as an equilateral triangle, is a straightforward process. A regular triangle has all three sides of equal length, making the calculation simple and quick.


Formula to Find the Perimeter of a Regular Triangle

The perimeter \( P \) of a regular triangle ABC can be calculated using the following formula:


\[ P = AB + BC + AC \]


Where:

- \( P \) represents the perimeter of the triangle.

- \( AB \), \( BC \), and \( AC \) are the lengths of the sides of the triangle.


In a regular triangle, all sides are equal, so if \( s \) is the length of one side, the formula simplifies to:


\[ P = 3s \]


Explanation of the Formula

The formula \( P = AB + BC + AC \) sums the lengths of all three sides of the triangle. Since all sides of a regular triangle are equal, we can simplify this to \( P = 3s \), where \( s \) is the length of one side.


Step-by-Step Calculation

Let's go through an example to illustrate how to use this formula.


Example:

Given a regular triangle ABC with each side length:

- \( s = 5 \) units


We want to find the perimeter of the triangle.


Step 1: Identify the Given Values

Given:

- \( s = 5 \) units


Step 2: Substitute the Values into the Formula

Using the simplified formula for a regular triangle:


\[ P = 3s \]


Substitute \( s \) with 5:


\[ P = 3 \cdot 5 \]


Step 3: Calculate the Perimeter

\[ P = 15 \]


Final Value

The perimeter of a regular triangle ABC with each side length \( s = 5 \) units is 15 units.


Using this simple formula, you can quickly determine the perimeter of any regular triangle, making it a useful tool for various applications in geometry and real-life scenarios.

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