The Lesson

A scalene triangle is a triangle where none of the sides or angles are equal.

Note: The lines through the two sides of the triangle in the image above indicate they are of equal length. The two arcs indicate the two angles are equal.

Dictionary Definition

The Merriam-Webster dictionary defines a scalene triangle as "having the three sides of unequal length."

Real Examples of Scalene Triangles

Below are real examples of scalene triangles.

In each case
  • No sides are the same length.
  • No angles are the same (60°).

What's in a Name?

'Scalene' comes from the Greek word "skalenos", meaning 'unequal'.

Interior Angles of a Scalene Triangle

The interior angles of any triangle add up to 180°. In a scalene triangle, the angles are all different.

Symmetry of a Scalene Triangle

A scalene triangle has no lines of symmetry.

Interactive Game on the Types of Triangle

Here is an interactive game to help you learn about the types of triangle.