The perimeter of a triangle is one of the most basic yet important concepts in geometry. It helps you measure the total boundary of any triangular shape, whether in maths, construction, or daily life calculations. By simply adding the lengths of all three sides, you can determine how much distance surrounds the triangle. This formula is used in geometry exams, aptitude tests, and real-life measurements like fencing or layout planning.
Formula for Calculating the Perimeter of a Triangle – Overview
| Formula | Variables & Meaning | When It Is Used |
|---|---|---|
| P = a + b + c | a, b, c = lengths of the triangle’s three sides | To find the total boundary length of a triangle in geometry, construction, or exams |
What is Perimeter in Maths?
In mathematics, the perimeter of a triangle refers to the total distance around its sides. It tells you the exact measurement of the boundary of the shape. The formula P = a + b + c means that you simply add the three side lengths to get the perimeter.
This formula works for all types of triangles - scalene, isosceles, and equilateral.
- For an equilateral triangle, where all sides are equal: P = 3a
- For an isosceles triangle, where two sides are equal: P = 2a + b
Perimeter is commonly used in real-world settings like fencing land areas, designing triangular structures, and calculating boundaries. It is also frequently asked in exams such as CUET, SSC, JEE, and Banking aptitude.
Examples to Calculate Perimeter of a Triangle
Example 1: Sides = 7 cm, 8 cm, and 5 cm
Step 1: Formula → P = a + b + c
Step 2: P = 7 + 8 + 5
Step 3: P = 20 cm
So, the perimeter of the triangle is 20 cm.
Example 2: Equilateral Triangle with each side = 6 m
Step 1: Formula → P = 3a
Step 2: P = 3 × 6
Step 3: P = 18 m
So, the perimeter of an equilateral triangle with each side 6 m is 18 m.
FAQs about Perimeter of a Triangle Formula
Q1. What is the perimeter of a triangle?
It is the total sum of all three sides of a triangle.
Q2. How do you find the perimeter of an equilateral triangle?
Multiply one side by 3 using the formula P = 3a.
Q3. Is perimeter different from area?
Yes. Perimeter measures the boundary length, while area measures the space inside the triangle.
Q4. Can perimeter be in decimals?
Yes. If sides are in decimals, add them normally to get the perimeter.
Q5. Why is perimeter important in exams?
It is a basic geometry concept and often appears in CUET, SSC, JEE, Banking, and school-level exams.
Q6. Does the perimeter formula change for different types of triangles?
No. The formula P = a + b + c remains the same; only the side lengths vary.