sine curve between fixed points

Dear all,

I'm new to grasshopper, and I'm trying to make a sine curve between fixed point (that can mannually be shifted while the sine curve stays the same) this is as far as I got (see attached files), the problem however is that I don't know how to handle the angle input in the point polar function so that my sine curve is perpendicular to the invisible line between the two points no matter where I shift them in my xy plane.

I hope it is clear what I'm asking, please see the attached files below.

David