Wonder Tape and sticky fingers

*finally*  -- success in the geometry of points across an an arc. 

First, I marked the points with a water soluble pencil:

Then, I cut out the triangles and tacked them down with Wonder Tape.  I love this stuff -- for pockets, zippers, applique -- anything, really.

 (wonder tape review).

Next, I lined up all the red/white triangles and seams and used Wonder Tape to hold them down.     

                   

Here's another pic of all the triangles taped down and ready to top-stitch!  Woohoo!