I have a quote from a friend that is suggecting that the Great Pyramid of Cheops was built upon the mathematical premise of the Earth hemisphere. I would like to know is this is possible and how would they to know the diameter?

"It's pretty clear that the Great Pyramid of Cheops is a mathematical model of the Earth. Specifically the northern hemisphere.

If you were ...to cut the Earth in half at the equator, measure its diameter and height it is the exact same proportions as the Great Pyramid of Cheops at a ratio of 1:43,200.

Calling this a coincidence would be rather absurd. And we know that they didn't have technology or the ability to measure these things in 2,500BC.

That and the evidence of water erosion on the The Sphinx, would demonstrate to any college student that it had to be built at a time when Egypt was not a desert. There would have had to have been significant rainfall on a consistent basis for thousands of years for it to erode in the way that it has."

And in addition give me this youtube video by Graham Hancock