# Angle

In Euclidean geometry, an **angle** is the figure formed by two rays, called the *sides* of the angle, sharing a common endpoint, called the *vertex* of the angle.[1]
Angles formed by two rays are also known as * plane angles* as they lie in the plane that contains the rays. Angles are also formed by the intersection of two planes; these are called

*dihedral angles*. Two intersecting curves may also define an angle, which is the angle of the rays lying tangent to the respective curves at their point of intersection.

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The magnitude of an angle is called an **angular measure** or simply "angle". **Angle of rotation** is a measure conventionally defined as the ratio of a circular arc length to its radius, and may be a negative number. In the case of a geometric angle, the arc is centered at the vertex and delimited by the sides. In the case of a rotation, the arc is centered at the center of the rotation and delimited by any other point and its image by the rotation.