In geometry, an angle is a geometric object composed of two rays with a common endpoint. These two rays are called the edges of an angle, and their common endpoint is called the vertex of the angle. The general angle is assumed to be in Euclidean plane, but it can also be defined in Euclidean geometry. Angle is widely used in geometry and trigonometry.

Euclid, the father of geometry, once defined an angle as the relative inclination of two non-parallel straight lines in a plane. Proclos thinks that angle may be a trait, a quantifiable quantity, or a relationship. Oldham thinks that an angle is a deviation from a straight line, and Cabus of Antioch thinks that an angle is a space between two intersecting straight lines. Euclid thinks that an angle is a relationship, but his definitions of right angle, acute angle or obtuse angle are quantitative.

The extended data angle is in degrees, minutes and seconds.

The symbol of degree is 0, the symbol of minute is', and the symbol of second is "

For example, if the degree of an angle is 30 degrees, then use 30 degrees.

30 degrees 28 minutes 10 second is 30 degrees 28' 10 ".