Staet the angle between the two vectors:
but not sure.
Please help, appreciate all pointers!
If you mean that a is a vector making an angle of 100 degrees with the x-axis, up and to the right, and that b is an angle making an angle of 30 degrees with the x-axis, down and to the left, then you simply add those two angles. But I don't understand why you are giving two answers. Those two vectors have one angle between them.