Right triangle

Triangle containing a 90-degree angle

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 c {\displaystyle c} in the figure). The sides adjacent to the right angle are called legs (or catheti, singular: cathetus).

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