Classifying triangles

The seven types of triangle can be classified (grouped) according to their sides or interior angles as shown below. Click on any triangle to go to its detail page.

Classification of triangles by sides

3 sides equal
2 sides equal
No sides equal

Classification of triangles by angles

One angle exactly 90°
3 angles equal
All 3 angles less than 90°
One angle
more than 90°

Other triangle topics


Perimeter / Area

Triangle types

Triangle centers

Congruence and Similarity

Solving triangles

Triangle quizzes and exercises