In order to find the actual length of the shadow, we must first determine the angle of the shadow as viewed from the center of the Moon. The actual (not obliquely viewed) length of the shadow must certainly be directed along the line running from the sub-solar point to the cape's summit.
Since we have already determined the angles from the sub-solar point to the cape's top (aka the shadow's base) and from the sub-solar point to the shadow's tip, we can simply subtract these two angles to find the angle of the shadow viewed from the center of the Earth, as measured along the line from the sub-solar point to the cape's summit:
Dg = gtip - gtop
The value should be at or near:
Dg = 0o.7032254
7 - Shadow Angle was Last Updated on December 06, 2010