# Angle

## Figure formed by two rays meeting at a common point / From Wikipedia, the free encyclopedia

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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.

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.