Need help figuring out the formula.

[Cguilford]

What formula or formulas would I use to solve for an angle between an object and its offset nested in side it's self. Please see PDF for refrence.
Thank you.

 

[Dr.Peterson]

Please just attach a picture and make it easy on everyone:


Please also explain in words what you did here, so we can be sure what it means.

 

[Cguilford]

How would I find the angle of the line created by the intersect of two parallel lines crossing two concentric circles? Both the parallel lines and concentric circles share a 2.5 offset.