Calculate lengths of inner, mid, outer arcs of elbow curve

I know this might be more of a math question, but I figured I would try. Attachment 865106I am trying to figure out the lengths of R3 (Spine length), R2, and R1. I know that D1 equals 6" and that the Center Line Radius is 1.5. I also know that T1 and T2 are both 9" (I don't think these matter though). Can anyone help me? I'm trying to make an excel that will allow me to change the diameter and CLR and give me R3, R2, and R1.