Angle ‒ Size

Circular arc

Value of an circular arc of angle AVB equals to the length of the arc AB, which is the intersection point of AVB and the circle centered in V and with radius of 1. The unit of an circular arc is called the radian (represented by symbol rad).

Radian is the main unit of plane angle. It belongs among the so-called. "Derived units" of the International System of Units SI.

Radian is mainly used in technical disciplines, such as physics or electrotechnics. Measures of angles are generally stated in degrees.



Arc degree

Arc degree was derived from the size of the equilateral triangle, which has been subdivided into 60 parts. Therefore, this measure is also called sexagesimal system. Full angle has a total of 360 units. Arc degree's unit rate is 1 degree, which is usually denoted by º.

Following applies to the one degree:



1º = π / 180rad



Angular degree is divided into 60 angular minutes (1º = 60')

Angular minute is divided into 60 angular seconds (1 '= 60"), i.e. 1º = 3600"



Radian and angular degree are the two most commonly used units of angles measurement. Other angular units are used in special disciplines but normally are not encountered.