cosθ-cosθ' = const. Bisector exact straight line
cf. Parent concept linkage is cosθ-cosθ' = const. exact straight line Linkage
Bisector linkage is below.
cf. Line Symmetry Linkage (Alias: Imai's Butterfly)
by Kempe, A. B. (Alfred Bray), 1849-1922
Above sample: 16 bars are too many. Please more simple.