Android Custom View Basics - Radians and Angles

radians and angles

1. What is radian and angle

1. Arc

Two rays are emitted from the center of the circle to the circumference, forming an included angle and an arc that is directly opposite to the included angle. When the arc length is exactly equal to the radius of the circle, the angle between the two rays is 1 radian

2. Angle

Two rays are emitted from the center of the circle to the circumference, forming an included angle and an arc that is directly opposite to the included angle. When the arc length is exactly equal to 1/360 of the circumference of the circumference, the angle between the two rays is 1 degree,
as shown in the figure:

The conversion relationship between radian and angle

rad is radians, deg is degrees

rad = deg x π / 180
deg = rad x 180 / π

π = 180