How many different types of triangle are there?

Answer 1

For the "catch all" and most broad type of triangles, there are 3:

Obtuse - 1 angle > 90°

Acute - all angles < 90°

Right - 1 angle exactly 90°

There are more specific categories, such as isosceles triangles, which can be obtuse, right or acute triangles that contain exactly 2 angles of equal degree, and exactly 2 sides of equal lengths.

Answer 2

There are three primary types of triangle - the equilateral, where all three sides are equal in length - the isoceles, where only two sides are equal in length - and the scalene, where no sides are equal in length.

The right triangle, where one angle is 90 degrees, is a special case of isoceles or scalene.