RIGHT ANGLE

In geometry and trigonometry, a 'right angle' is defined as an angle between two straight intersecting lines of ninety degrees, or one-quarter of a circle. Right angles are perpendicular, and have important properties in mathematics. The presence of a right angle in a triangle is the defining factor for right triangles.
A right angle may be expressed in different units:

★ 90°

★ When a straight line standing on a straight line makes the adjacent angles equal to one another, each of the equal angles is right—in Euclid's Elements

★ full circle

★ rad

★ Babylonian unit

★ 100 grad (also called grade, gradian, or gon)

★ 8 points (of a compass rose)

★ 6 hours (astronomical hour angle)

★ The angle of perpendicularity

★ ∞% grade on the tangent scale

★ 100% grade on the sine scale.

Contents

See also

See also

★ Angle: Types of angles

★ Orthogonality

★ Perpendicular

★ Cartesian coordinate system

★ Rectangle