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# Perimeter of Triangle – Definition, Formula & Examples

August 31, 2022

The perimeter of any 2D figure is defined as the distance around the figure. You can find the perimeter of any plane figure (2D shape) by adding the length of each side of the figure. Since the perimeter of any figure is a linear measurement, it is expressed in terms of unit, such as mm, cm, m, ft, yd, in, etc.

Let’s learn what is the perimeter of a rectangle and how it is calculated.

## Triangle – A 2D Plane Figure

A triangle is a three-sided polygon formed by joining three non-collinear points known as the vertices (singular vertex). The line segments joining the three points (vertices) are called the sides (edges) of a triangle. The region formed between any of the two sides/edges of a triangle is called an angle of a triangle. There are three angles in a triangle whose sum is always $180^{\circ}$.

Triangles are broadly classified under two classifications

• Classification based on sides
• Scalene Triangle: A triangle with no side equal
• Isosceles Triangle: A triangle with any two sides is equal
• Equilateral Triangle: A triangle with all three sides are equal
• Classification based on angles
• Acute Triangle: A triangle where all three angles acute angles $\left(\lt 90^{\circ} \right)$
• Obtuse Triangle: A triangle where one of the angles is an obtuse angle $\left(\gt 90^{\circ} \right)$
• Right Triangle: A triangle where one of the angles is a right angle $\left(= 90^{\circ} \right)$

## What is the Perimeter of Triangle?

The perimeter of a triangle is the total length of all three sides of a triangle. Thus, the perimeter of a triangle is obtained by adding the length of the three sides of a triangle. Since the perimeter is a linear measure, therefore, the unit of the perimeter of a rectangle will be in metre, centimetre, inch, feet, etc.