Create an arc with a specified radius.

Input parameters:

1. Pl → Arc base plane.
2. Pa → Arc start point.
3. Pb → Arc end point.
4. Rd → Arc radius.

Output parameters:

1. LL → Left-most arc of the left circle solution.
2. LR → Right-most arc of the left circle solution.
3. RL → Left-most arc of the right circle solution.
4. RR → Right-most arc of the right circle solution.