Right angle

Right angle

In geometry and trigonometry, a right angle is an angle of 90 degrees, corresponding to a quarter turn (that is, a quarter of a full circle). It can be defined as the angle such that twice that angle amounts to a half turn, or 180° [Lindahl, G. (1987). "Euklides Geometri". Stockholm, Natur och kultur: ISBN 91-27-72185-X] .

Lines that are at a right angle to each other are perpendicular, an important geometrical property. 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°
*π/2 radians
*100 grad (also called "grade", "gradian", or "gon")
*8 points (of a 32-point compass rose)
*6 hours (astronomical hour angle)
*∞% grade on the tangent scale
*100% grade on the sine scale.

In mathematics, right angle can be an additional unit of angle [* [http://www.convertworld.com/en/angle/ convertworld.com angles] ] . 1r=90°=π/2 rad=100g

The term is a calque of Latin "angulus rectus"; here "rectus" means "upright", referring to the vertical perpendicular to a horizontal base line.

See also

*
*Orthogonality
*Perpendicular
*Cartesian coordinate system
*Rectangle

References


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  • Right angle — Angle An gle ([a^][ng] g l), n. [F. angle, L. angulus angle, corner; akin to uncus hook, Gr. agky los bent, crooked, angular, a gkos a bend or hollow, AS. angel hook, fish hook, G. angel, and F. anchor.] 1. The inclosed space near the point where …   The Collaborative International Dictionary of English

  • Right angle — Right Right (r[imac]t), a. [OE. right, riht, AS. riht; akin to D. regt, OS. & OHG. reht, G. recht, Dan. ret, Sw. r[ a]tt, Icel. r[ e]ttr, Goth. ra[ i]hts, L. rectus, p. p. of regere to guide, rule; cf. Skr. [.r]ju straight, right. [root]115. Cf.… …   The Collaborative International Dictionary of English

  • right angle — right angles also right angle 1) N COUNT A right angle is an angle of ninety degrees. A square has four right angles. 2) PHRASE: oft PHR to n If two things are at right angles, they are situated so that they form an angle of 90° where they touch… …   English dictionary

  • right angle — right ,angle noun count an angle of 90° at right angles to/at a right angle to if one thing is at right angles to another thing, they form an angle of 90 degrees at the point where they meet ╾ right ,angled adjective …   Usage of the words and phrases in modern English

  • right angle — right .angle n 1.) an angle of 90°, like the angles at the corners of a square 2.) at right angles (to sth) if two things are at right angles, they make a 90° angle where they touch ▪ Hold the brush at right angles to the surface. >right… …   Dictionary of contemporary English

  • right angle — ► NOUN ▪ an angle of 90°, as in a corner of a square. ● at right angles to Cf. ↑at right angles to DERIVATIVES right angled adjective …   English terms dictionary

  • right angle — n. an angle of 90 degrees; angle made by the meeting of two straight lines perpendicular to each other: see ANGLE1 …   English World dictionary

  • right angle — UK / US noun [countable] Word forms right angle : singular right angle plural right angles maths an angle of 90° • at right angles to/at a right angle to if one thing is at right angles to another thing, they form an angle of 90 degrees at the… …   English dictionary

  • right-angle — (ˈ) ̷ ̷| ̷ ̷ ̷ ̷ verb Etymology: right angle transitive verb : to bend, direct, or locate at a right angle white benches were right angled to every doorstep Anna Cunningham …   Useful english dictionary

  • right angle — noun Date: 15th century the angle bounded by two lines perpendicular to each other ; an angle of 90° or 1/2 π radians • right angled or right angle adjective …   New Collegiate Dictionary

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