In mathematics and physics, radian is the unit of measurement of angle. It is a unit derived from the international system of units, abbreviated as rad. Definition: an arc whose arc length is equal to the radius and whose central angle is 1 radian. (that is, two rays shoot from the center of the circle to the circumference, forming an arc with an angle opposite to the angle. When the arc length is exactly equal to the radius of the circle, the radian of the included angle between two rays is 1).
The central angle 1/360 of the circumference is called 1 degree angle, and it is recorded as 1 degree, 1 degree =60 minutes (1 degree = 60'), and 1 minute equals 60 seconds (/. Because the angle system is hexadecimal, it is often difficult to convert units when calculating the addition and subtraction of two angles.
Therefore, in mathematics and scientific research, another method is often used to measure angles: the central angle of an arc with a long radius is called 1 radian angle, and it is recorded as 1(rad). For the convenience of calculation, 1 radian =206265 seconds, which is often quoted directly. Rad is called radian angle, which is very commonly used in mathematical calculation and physical calculation. Conversion method of radian and angle: rad=degree*pi/ 180. 1 radian is approximately equal to 57.3 degrees.