Help on difficult math problems!!!?

[huskies]

There are two versions of how Thales calculated the height of an Egyptian pyramid by shadows. The warlies account, given by Hieronymus, a pupil of Aristole, says that Thales noted the length of the shadow of the pyramid at the moment when his shadow was the same length as himself. The later version, given by Plutarch, says that he set up a stick and then made use of similar triangles. Both versions fail to mention the difficulty, in either case, of obtaining the length of the shadow of the pyramid-that is, the distance from the apex of the shadow to the center of the base of the pyramid.
Devise a method, based on similar triangles and independent of latitude and time of year, for determining the height of a pyramid from two shadow observations.