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## Main Question or Discussion Point

The following discussion is in 2 dimensions:

Take two vectors, A and B. Generally we find the angle (theta) between them by

cos(theta) = dot(A,B) / (norm(A) * norm(B))

however, take vector A to be [0, 1] (straight up)

If vector B is [1,1], the angle between them is pi/4 radians. If vector B is [-1, 1], the angle between them is STILL pi/4 radians!!

I need to know the signed angle between them (one of the B's above should be -pi/4, the other, pi/4). How would I do that?

Thanks!

Dave

Take two vectors, A and B. Generally we find the angle (theta) between them by

cos(theta) = dot(A,B) / (norm(A) * norm(B))

however, take vector A to be [0, 1] (straight up)

If vector B is [1,1], the angle between them is pi/4 radians. If vector B is [-1, 1], the angle between them is STILL pi/4 radians!!

I need to know the signed angle between them (one of the B's above should be -pi/4, the other, pi/4). How would I do that?

Thanks!

Dave