Double Math

# Angle in Math, Concept of an Angle,

Angle in Math: Two rays with a common starting point form an angle. One of the rays of angle is called the initial side and the other is the terminal side. The angle is identified by showing the direction of rotation from the initial side to the terminal side.
An angle is said to be positive/negative if the rotation is anti-clockwise/clockwise. Angles are usually denoted by Greek letters such as \alpha (alpha), \beta(beta),\gamma (gamma), \theta (theta) etc.

There are two commonly used measurements for angle (in math): Degrees and Radians. which are explained as below:

• Sexagesimal System:(Degree, Minute and Second)

If the initial ray \overline{OA} rotates in an anti-clockwise direction in such a way that it coincides with itself, the angle then formed is said to be of 360 degrees (360^\circ)
One rotation (anti-clockwise) = 360^\circ

\frac12rotation (anti-clockwise) = 180° is called a straight angle

\frac14rotation (anti-clockwise) = 90° is called a right angle

1 degree (1°) is divided into 60 minutes (60′) and 1 minute ( 1’) is divided into 60 seconds
(60′′). As this system of measurement of angle owes its origin to the English and because 90,
60 are multiples of 6 and 10, so it is known as the English system or the Sexagesimal system.

Thus

1 rotation (anti-clockwise) = 360°.
One degree (1°) = 60’
One minute (1′) = 60”