The location that is StationC =. Station# 234.5 to Station# 329.2 (extant z161) = 94.7ft + 5.3ft = Station# 334.5 = distance of 100ft = the intersection of (Zapruders LOS and Robert West's path) then back to the WC labeled PositionA = the hypotenuse.  Of course 5.3ft being the Pivot of PositionA into a right triangle. Let the WC confirm that for you: