# Classification of triangles

# Triangles differentiated on the basis of their sides

## Equilateral Triangles:

A triangle with all sides equal to one another is called an equilateral triangle.

## Isosceles Triangle:

A triangle with a pair of equal sides is called an isosceles triangle.

## Scalene Triangle:

A triangle in which all the sides are of different lengths and no two sides are equal, the triangle is called a scalene triangle.

# Triangles differentiated on the basis of their angles.

## Acute angled triangle.

A triangle whose all angles are acute is called an acute-angled triangle or simply an acute triangle.

## Right angle triangle

A right triangle has one angle 90°

## Right Isosceles Triangle

If a triangle has a right angle (90°), and also two equal angles, can you guess what the equal angles are?

## The Obtuse Triangle

The Obtuse Triangle has an obtuse angle (an obtuse angle has more than 90°). In the picture on the left, the shaded angle is the obtuse angle that distinguishes this triangle. Since the total degrees in any triangle is 180°, an obtuse triangle can only have one angle that measures more than 90°.

*** for geogebra link on types of triangles** [click here ]

# Angles in a triangle

## Interior angles of a triangle

The interior angles are those on the inside of the triangle.

## Exterior Angles of a triangle

An exterior angle is formed by extending any side of the triangle.

**Image Acknowledgement: Mathsisfun.com**