It is legendarily told that, by the time of 550 BC, Pharaoh Amasis wished to build up a pyramid higher than the Cheops's one -- then, there was the need to know the measures of this pyramid. However, it was not an easy task: to measure the height of an oblique façade solid.
Someone suggested to the pharaoh the name of a Greek man who lived in Mileto -- Thales. To solve the problem, this geometrician man traveled to Egypt, going to the Giza upland to execute the measurement. There, the Greek man waited until the sunset. After some time, he said to astonished Egyptian people: "I will be back in propitious times with the Cheop's pyramid height." Then, he went to Greece -- and the Egyptian wise man became perplexed and suspicious. When would come these propitious times?
As he promised, Thales came back to Egypt on October. Before the sunset, he went to the Giza upland. He measured his own height, making a mark on the sand congruently to this height, and waited until the Sun could stay on a perpendicular plan beside one of the basis side huge pyramid, whose giant shadow was projected on the ground. The Thales shadow, much smaller than that, was also projected. After that, by his order, it was made a mark congruently to the pyramid shadow when his own shadow achieved the same length of his height marked on the ground. Taking this length, and considering that the ratio between the pyramid height and its respective shadow was the same as the ratio of his own height and his shadow, he concluded the pyramid was 85 times higher than his height.
Nowadays, measuring the height on anything, mainly this Egyptian pyramid, is a very trivial task and, thus, there is nothing new in this article about it. Nevertheless, don't you think it is interesting that with these data we can calculate the height of a genius man who was born 2632 years ago? ;)