What is the arc degree of the circle angle whose arc length is equal to radius? Such as the title

What is the arc degree of the circle angle whose arc length is equal to radius? Such as the title

If the arc length is L = a * r (a is the arc of the center angle, R is the radius of the circle), the arc of the center angle with the arc length equal to the radius is 1, and the arc of the circle angle is 1 / 2

There are many questions. Thank you first
First of all, can the set of the same angle a {a | a = β + 360 * k} with the terminal edge of an arbitrary angle β be understood as rotating K cycles and then rotating a β with the positive half axis of X as the starting edge? For example, K is a negative integer and β is a positive angle. Does it mean rotating K cycles clockwise and then rotating a β anticlockwise?
2. As for the comparison of angles, if two positive angles compare, is it a direct comparison of degrees, but how about two positive angles? One positive angle and one negative angle?
3. About a quadrant angle, such as the first quadrant angle, why is {a | 360K

1. That's understandable. Absolutely right
2. A simple angle comparison is the same as a real number comparison. A positive angle is greater than all negative angles
The difference between angle and trigonometric function of angle is
3. At this time, a is no longer in the range of 0-360 degrees
It can only be {a | 360K

How to prove the cubic power of sin3x = 3sinx + 4 (SiNx)

sin3x
=sin(x+2x)
=sinx*cos2x+cosx*sin2x
=sinx(1-2sinx^2)+cosx*2sinx*cosx
=sinx-2sinx^3+2sinx*(1-sinx^2)
=3sinx-4sinx^3