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Straight Angle

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StraightAngle

A straight angle is an angle equal to 180 degrees=pi radians.

The sides of a straight angle are opposite rays. They lie on the same line but point in opposite directions. Viewed as a rotation from one side to the other, a straight angle is a half-turn. Unlike a line, a straight angle has a specified vertex.

In the illustration, the opposite rays OA and OC form the straight angle ∠AOC=180 degrees=pi radians.

Two right angles make a straight angle, and the two angles of a linear pair form a straight angle. Two straight angles make a full angle.

See also

Acute Angle, Angle, Digon, Full Angle, Half-Turn, Linear Pair, Obtuse Angle, Reflex Angle, Right Angle

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References

Hadamard, J. Lessons in Geometry, I: Plane Geometry. Providence, RI: Amer. Math. Soc., 2008.Rusczyk, R. Introduction to Geometry, 2nd ed. Alpine, CA: AoPS Inc., pp. 21-23, 2007.

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Straight Angle

Cite this as:

Weisstein, Eric W. "Straight Angle." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/StraightAngle.html

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