Angle from 2D unit vector?

Question

Given unit vector (0.5, 0.5) how could I find the angle (its direction)?

Is it cos(x) + sin(y)?

Answer 1

Given y and x, the angle with the x axis is given by:

atan2(y, x) // note that Y is first

With (0.5, 0.5) the angle is:

radians:

In [2]: math.atan2(0.5, 0.5)
Out[2]: 0.7853981633974483

degrees:

In [3]: math.atan2(0.5, 0.5)*180/math.pi
Out[3]: 45.0