Right angle
From Wikipedia, the free encyclopedia
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° in Euclid's Elements
- 1/4 full circle
- π/2 rad
- 3/2 Babylonian unit
- 100 grad (also called grade, gradian, or gon)
- 8 points (of a compass rose)
- 6 hours (astronomical hour angle)
[edit] Related angles
The difference between an angle and a right angle is termed the complement of the angle.
