Finding the rotation angle between two vectors in the first quadrant

[Saladsamurai]

Okay then!

Let's say we are ONLY working in the 1st Quadrant of the x-y plane. I have some vector in that region that makes some angle with the +x axis. I then rotate that vector through some angle.

The initial points of the vector before and after are coincident, i.e. I only move the terminal end to some new point while maintaining the vectors magnitude.

I know the initial point, I know the terminal points of both the original and new vector.

I now need the angle that I must have rotated through to get to the new point.

Is this a dot product problem?

 

[kuruman]

That's what it is.

 

[Saladsamurai]

Alrighty-then!