Pyramid Azimuths
It is currently my belief that the Great Pyramid and others were aligned to the equinoctial Sun. The slight westward deviation would then be due to the fact that the Sun doesn't rise exactly due East on the equinoxes but slightly North of East on one day and slightly South of East the next. If the Egyptians were to align to the equinoctial Sun on the same date every year the exact angle of alignment would vary slightly from one year to the next and it would rarely be exactly due East. It can be only a few arc minutes off from due East one year and 15 or more arc minutes off the next, so there is no way to deduce the actual date of construction of the pyramids from their azimuths because the variation is too unpredictable.
What makes me think the pyramids were aligned to the Sun rather than to certain stars? Well, the causeways from the Great and Second Pyramids are aligned to the sunrise 30 days before and 30 days after the equinoxes respectively. That is three Egyptian weeks of 10 days. My guess is that they would have held some kind of 30 day ceremony leading up to the equinox and possibly a similar one after. What other purpose could the causeway angles have? They don't correspond to the "cross quarter point" sunrises, as suggested by some. That would be more like six weeks each side of the equinoxes. So it appears that Giza is very much concerned with the equinoctial sunrise, which makes sense when you recall that Khufu proclaimed himself to actually be the Sun god Re himself and both Khafre and Menkaure have the name of Re in their names.
No stellar alignment theory can explain Khafre's Pyramid azimuth being further West than the Great Pyramid's. Only a solar alignment at the equinoxes can produce such seemingly random fluctuations. Sometimes the equinox sunrise is slightly South of due East instead of slightly West. In 2505 BC, for instance, on October 14th the Sun rose at almost 14 arc minutes South of due East. That's the same day that the Sun rose at slightly North of due East in years such as 2593 and 2597 BC, matching the Great Pyramid's azimuth.
Great Pyramid Shape
My theory on the shape of the Great Pyramid is that it was designed and laid out in a unit called the "Nippur Cubit", rather than cubits. I previously thought the dimensions were in "double remens" because the sides are very close to 311 double remens, which would be part of the pi fraction 311/99. A nagging problem with this theory was that the diagonals of the Great Pyramid's base should have been 622 royal cubits but is in fact slightly less than that. The only theory which explains the diagonals satisfactorily is one involving the Nippur Cubit.
Being that the Great Pyramid's height is 280 royal cubits, it would convert to (100 x sqrt 2) x 2 Nippur Cubits (NC for short), which is 282.8427125. That length is easily obtained as the diagonal of a 400 NC square. Multiplying that by pi yields 1777.153175 NC as the perimeter of a perfect squared circle type pyramid. Not knowing the exact value of pi, I believe that the Egyptians used a fractional version of pi, such as 311/99, to calculate the perimeter. That would yield 1777.052194 NC, which would have been rounded off to 1777 for simplicity. That would make each side of the pyramid 444.25 NC, producing a diagonal of 628.2643751 NC (2 pi) or about 621.9465 royal cubits. Using Flinders Petrie's survey coordinates for the Great Pyramid's corner positions we obtain diagonals of 621.966 RC from the NW to SE corners and 621.89 RC from NE to SW, the pyramid being slightly off square. As you can see, these are almost the exact theoretical length for my NC theory. The average of the two diagonals is 621.928, only about 2/100ths of a cubit difference from the theoretical 621.9465 cubits. about 0.4 inch. I'm using Petrie's royal cubit length for this, 20.62 inches.
So at the present time I can find no better explanation for the Great Pyramid's dimensions than that it is a representation of a discovery by the Egyptians or the Mesopotamians (who created the NC) that a circle with diameter the diagonal of a 400 NC square has a circumference of almost exactly 1777 NC. Why did they not simply use the same number of royal cubits instead of NC? Could have been some religious reason. Maybe that early discovery was seen as a sacred thing not to be altered in any way, such as using different units. All I know is that the diagonals of the pyramid's base confirm this NC hypothesis very nicely and that I can find no other explanation for the diagonals being slightly under 622 RC, which they would certainly have rounded off to if they were in fact using RC for the design. That would have made things much easier. They would have rounded off either the side dimensions or the diagonal dimensions for easy laying out. The sides have not been rounded off to 440 cubits, because they are actually around 439.8, so neither the sides nor the diagonals are in practical numbers of RC but the sides are in a practical number of NC because it is an even quarter unit, 444.25, which is easy to measure out.. The builders appear to have employed royal cubits in the interior structures but the outer shape is clearly in NC.