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Right angle
 
 
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In geometry
Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers....
 and trigonometry
Trigonometry

Trigonometry is a branch of mathematics that deals with triangle s, particularly those plane triangles in which one angle has 90 degrees . Trigonometry deals with relationships between the sides and the angles of triangles and with the trigonometric functions, which describe those relationships....
, a right angle is an angle of 90 degree
Degree (angle)

A degree , usually denoted by ? , is a measurement of plane angle, representing 1/360 of a Turn ; one degree is equivalent to p/180 radians....
s, corresponding to a quarter turn (that is, a quarter of a full circle). It can be defined; as the angle
Angle

In geometry and trigonometry, an angle is the figure formed by two Ray sharing a common endpoint, called the vertex of the angle . The magnitude of the angle is the "amount of rotation" that separates the two rays, and can be measured by considering the length of circular arc swept out when one ray is rotated about the vertex to coincide...
 such that twice that angle amounts to a half turn, or 180°.

Lines that are at a right angle to each other are perpendicular
Perpendicular

In geometry, two line or plane , are considered perpendicular to each other if they form congruence adjacent angles angles . The term may be used as a noun or adjective....
, an important geometrical property. The presence of a right angle in a triangle
Triangle

A triangle is one of the basic shapes of geometry: a polygon with three corners or wikt:vertex and three sides or edges which are line segments....
 is the defining factor for right triangles.

A right angle may be expressed in different units:

In mathematics, right angle can be an additional unit of angle.






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In geometry
Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers....
 and trigonometry
Trigonometry

Trigonometry is a branch of mathematics that deals with triangle s, particularly those plane triangles in which one angle has 90 degrees . Trigonometry deals with relationships between the sides and the angles of triangles and with the trigonometric functions, which describe those relationships....
, a right angle is an angle of 90 degree
Degree (angle)

A degree , usually denoted by ? , is a measurement of plane angle, representing 1/360 of a Turn ; one degree is equivalent to p/180 radians....
s, corresponding to a quarter turn (that is, a quarter of a full circle). It can be defined; as the angle
Angle

In geometry and trigonometry, an angle is the figure formed by two Ray sharing a common endpoint, called the vertex of the angle . The magnitude of the angle is the "amount of rotation" that separates the two rays, and can be measured by considering the length of circular arc swept out when one ray is rotated about the vertex to coincide...
 such that twice that angle amounts to a half turn, or 180°.

Lines that are at a right angle to each other are perpendicular
Perpendicular

In geometry, two line or plane , are considered perpendicular to each other if they form congruence adjacent angles angles . The term may be used as a noun or adjective....
, an important geometrical property. The presence of a right angle in a triangle
Triangle

A triangle is one of the basic shapes of geometry: a polygon with three corners or wikt:vertex and three sides or edges which are line segments....
 is the defining factor for right triangles.

A right angle may be expressed in different units:
  • 90°
  • p/2 radian
    Radian

    The radian is a unit of plane angle, equal to 180/pi Degree , or about 57.2958 degrees, or about 57?17'45?. It is the standard unit of angular measurement in all areas of mathematics beyond the elementary level....
    s
  • 100 grad
    Grad (angle)

    The grad is a unit of plane angle, equivalent to of a full circle, dividing a right angle in 100. It is also known as gon, grade, or gradian ....
     (also called grade, gradian, or gon)
  • 8 points (of a 32-point compass rose
    Compass rose

    For Compass Airlines, an Airline in the US using the Callsign "Compass Rose," See Compass Airlines A compass rose is a figure displaying the Orientation of the Cardinal directions, north, south, east and west on a map or nautical chart....
    )
  • 6 hours (astronomical hour angle
    Hour angle

    In astronomy, the hour angle is one of the coordinates used in the equatorial coordinate system for describing the position of a point on the celestial sphere....
    )
  • 8% grade on the tangent scale
  • 100% grade on the sine scale.


In mathematics, right angle can be an additional unit of angle. 1r=90°=p/2 rad=100g

The term is a calque
Calque

In linguistics, a calque or loan translation is a word or phrase borrowed from another language by literal, word-for-word or root-for-root translation....
 of Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 angulus rectus; here rectus means "upright", referring to the vertical perpendicular to a horizontal base line.

See also

  • Types of angles
    Angle

    In geometry and trigonometry, an angle is the figure formed by two Ray sharing a common endpoint, called the vertex of the angle . The magnitude of the angle is the "amount of rotation" that separates the two rays, and can be measured by considering the length of circular arc swept out when one ray is rotated about the vertex to coincide...
  • Orthogonality
    Orthogonality

    In mathematics, two vectors are orthogonal if they are perpendicular, i.e., they form a right angle. The word comes from the Greek language ' , meaning "straight", and ' , meaning "angle"....
  • Perpendicular
    Perpendicular

    In geometry, two line or plane , are considered perpendicular to each other if they form congruence adjacent angles angles . The term may be used as a noun or adjective....
  • Cartesian coordinate system
    Cartesian coordinate system

    In mathematics, the Cartesian coordinate system is used to determine each Point uniquely in a Plane through two numbers, usually called the x-coordinate or abscissa and the y-coordinate or ordinate of the point....
  • Rectangle
    Rectangle

    In geometry, a rectangle is a Closed set planar quadrilateral with four right angles. A rectangle with vertices ABCD would be denoted as .A rectangle with adjacent sides of lengths a and b has area ab and diagonals of equal length ....