Right angle

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Villa Savoye, an example of modern architecture, designed with many right angles.
Villa Savoye, an example of modern architecture, designed with many right angles.

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.

[edit] See also

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