I have kind of a meta question about trigonometry!
Am I right in assuming that the following calculation/formula gives me the angle alpha between a two-dimensional vector and the x-axis of a plane (i.e. xy-plane)?
For the y-coordinate of the vector being bigger than 0:
- alpha = acos(vector x / vector length)
For the y-coordinate being smaller or equal to 0:
- alpha = 2 x Pi - acos(vector x / vector length)
Furthermore, how would I go about introducing 3D space into this? I mean calculating the angle for three-dimensional vectors? This would only be possible in the local plane of the vector and the x-axis, wouldn’t it?
As always, thanks.