why did Ra build the pyramids to align with the Orion Star Belt?

[MrWho]

This has been debunked. The original authors of this theory were not entirely truthful.

https://en.m.wikipedia.org/wiki/Orion_co...y#Critique

Among these are critiques from two astronomers, Ed Krupp of Griffith Observatory in Los Angeles and Tony Fairall of the University of Cape Town, South Africa. Using planetarium equipment, Krupp and Fairall independently investigated the angle between the alignment of Orion's Belt and north during the era cited by Hancock, Bauval, et al. (which differs from the angle seen today or in the third millennium BC, because of the precession of the equinoxes). They found that the angle was somewhat different from the "perfect match" thought to exist by Bauval and Hancock in the Orion correlation theory. They estimate 47–50 degrees per the planetarium measurements, compared to the 38-degree angle formed by the pyramids.[13]

Krupp pointed out that the slightly bent line formed by the three pyramids was deviated towards the north, whereas the slight "kink" in the line of Orion's Belt was deformed to the south, and to match them up one or the other of them had to be turned upside-down.[14] Indeed, this is what was done in the original book by Bauval and Gilbert (The Orion Mystery),[15] which compares images of the pyramids and Orion without revealing that the pyramids’ map had been inverted.[16]