Rotating Circles- constant length connecting line query

Hi everyone,

I'm hoping someone will please be able to give me advice regarding the below query.

I have drawn two parallel/offset circles, each with 20 points.  Lines connect the respective points across the circles (please see image below).  As the planes of the circles are offset by 100, the length of each of the lines is also 100.

I have set up a slider so that one of the circles can be rotated from -180 degrees to +180 degrees.

I would like the length of the connecting lines to remain constant, at 100, thus moving the circles closer together as one of the circles is rotated.  

I'm leaning towards using a range, and plugging in the rotation angle and length of the lines somehow, but am unclear as to how best to go about this.  I am new to grasshopper, so would very much appreciate any tips about the next step I should explore.

I've attached the grasshopper file and some images below.

Many thanks in advance!

Sarah