Right-angled triangle in the context of "Turn (unit)"

A right triangle or right-angled triangle, sometimes called an orthogonal triangle or rectangular triangle, is a triangle in which two sides are perpendicular, forming a right angle (1⁄4 turn or 90 degrees).

The side opposite to the right angle is called the hypotenuse (side ${\displaystyle c}$ in the figure). The sides adjacent to the right angle are called legs (or catheti, singular: cathetus). Side ${\displaystyle a}$ may be identified as the side adjacent to angle ${\displaystyle B}$ and opposite (or opposed to) angle ${\displaystyle A,}$ while side ${\displaystyle b}$ is the side adjacent to angle ${\displaystyle A}$ and opposite angle ${\displaystyle B.}$