What is a triangle?

A simple closed curve or a polygon formed by three line-segments (sides) is called a triangle.

What is a Triangle

The above shown shapes are triangles. The symbol of a triangle is .

A triangle has

  1. three line-segments or sides
  2. three vertices
  3. three angles

There are six types of triangles, 3 with respect to sides and 3 with respect to angles.

Three types of triangle with respect to sides

(i) A triangle having all the three line-segments or sides unequal is called a scalene triangle.

Scalene Triangle

Scalene Triangle

(ii) A triangle having a pair of its sides or two line-segments equal is called an isosceles triangle.

Here AB = AC.

Isosceles Triangle

Isosceles Triangle

(iii) A triangle having all the three line-segments or sides equal is called an equilateral triangle.

Here AB = BC = CA.

Equilateral Triangle

Equilateral Triangle

Types of triangle with respect to angles

(i) A triangle in which all the three angles are acute is called an acute angled triangle.

∠ABC, ∠ACB and ∠BAC are all acute angles.

 Acute Angled Triangle

Acute Angled Triangle

(ii) A triangle in which one of the three angles is a right angle is called a right angled triangle.

∠ABC = one right angle.

Right Angled Triangle

Right Angled Triangle

(iii) A triangle where one of the three angles is more than a right angle (or is an obtuse angle) is called an obtuse angled triangle.

∠ABC is an obtuse angle.

Obtuse Angled Triangle

Obtuse Angled Triangle

Math Only Math is based on the premise that children do not make a distinction between play and work and learn best when learning becomes play and play becomes learning.

However, suggestions for further improvement, from all quarters would be greatly appreciated.

Related Concepts on Geometry - Simple Shapes & Circle

Simple Closed Curves


Different Types of Polygons




Circle Math

Line Symmetry

Symmetrical Shapes

4th Grade Math Activities

From Triangle to HOME PAGE

New! Comments

Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.

Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.