**Sexagesimal system Degree minute second:** If the initial ray **OA Rotates** in **anticlockwise** direction in such a way that it **coincides with itself,** the angle then formed is said to be of **360 degree** (360°)

**(1) one rotation = 360°**

means one circle in anticlockwise

**(2) 1/2 rotation = 180°**

means half circle anticlockwise

**(3) 1/4 rotation= 90°**

mean quarter circle anticlockwise

**Sexagesimal system Degree minute second:**

**(i)one degree** means **mathematical sign (1°)** is divided into **60 minutes** means mathematical sign **(60′).**

**(ii) One minute (1′**) mean one rotation is divided into 60 seconds** mathematical sign (60”).**

As this system of measurement of angle own its origin

to the English and because 90, 60 are multiplies of 6 and 10, so it is known as** English system**. Or **Sexagesimal system**

Angle for all trigonometry

**1 rotation (anticlockwise)= 360°**

**One degree (1°) = 60′**

**One minute (1′)= 60″**

Title: Sexagesimal System: Degree, Minute, and Second

In the sexagesimal system, degrees, minutes, and seconds are used to measure angles and coordinate locations on a sphere. This system divides a circle into 360 degrees, each degree into 60 minutes, and each minute into 60 seconds. It provides a precise and widely accepted means of expressing angular measurements.

keep in mind r and l are measured in tern of the same unit and the radian measure in unit less, that is always a real number.

Example:

If r = 3 cm and l = 6 cm

then

θ = l / r = 6/ 3 =2

θ = 2

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