noun
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geometryan angle whose measure is equal to 90 degrees.
A perpendicular angle is a quarter of a full rotation. In radians, a perpendicular angle is equal to radians. In degrees, a perpendicular angle is equal to .
An acute angle is an angle that measures less than 90 degrees.
An obtuse angle is an angle that measures more than 90 degrees but less than 180 degrees. It is larger than a right angle and smaller than a straight angle.
A reflex angle is an angle whose measure is greater than 180 degrees but less than 360 degrees.
In mathematics, orthogonal refers to a concept involving right angles. In Euclidean space, two vectors are orthogonal if they are at right angles to each other. In linear algebra, two vectors are orthogonal if their dot product is zero.