Types of Triangles

Triangles types are named and classified by their sides and by their angles.

By Angle:
Acute Triangle — All angles are less than 90°.
Right Triangle — Has an angle that is exactly 90°.
Obtuse Triangle — Has one angle that is more than 90°.

By Side:
Equilateral Triangle — All three sides are equal in length.
Isosceles Triangle — Two sides are equal in length.
Scalene Triangle — Has no sides that are equal in length.