- Right Angle Triangle – A Right triangle is a triangle in which one angle is a right angle (that is, a 90-degree angle). The relation between the sides and angles of a right triangle is the basis for trigonometry (opposite, hypotenuse, adjacent).
- Obtuse Triangle – An obtuse triangle is a triangle with one obtuse angle (greater than 90°) and two acute angles.
- Acute Triangle – An acute triangle is a triangle with three acute angles (less than 90°).
