# Math's: Lines and Angles: Triangle: Meaning, Types and Properties

## Triangle- Meaning

A triangle is a closed figure formed on a plane by joining three collinear points by three-line segments. It has six elements-

• Three angles formed on the three points. ∠A, ∠B and ∠C in the given figure.

• Three sides that consist of the three-line segments. AB, BC and AC in the given figure.

## Types of Triangles

Triangles can be classified into different types on two bases-

### On the Basis of Sides

• Equilateral triangle: A triangle in which all the three sides are equal is called an equilateral triangle.

• Isosceles triangle: A triangle in which two sides are equal is called an isosceles triangle.

• Scalene triangle: A triangle in which all sides are of different lengths, is called a scalene triangle

### On the Basis of Angles

• Obtuse angled triangle: A triangle in which one of the angles is an obtuse angle is called an obtuse angled triangle or simply obtuse triangle.

• Right angled triangle: A triangle in which one of the angles is a right angle is called a right-angled triangle or right triangle.

• Acute angled triangle: A triangle in which all the three angles are acute is called an acute angled triangle or acute triangle.