Measuring angles, one soon finds them self immersed in basic geometry problems. The Pyramids, . . well, . . they’re very much about angles, geometric figures, inclinations, starry positions, and an ancient form of spiritual expression all combined into one it seems. I would think so, anyway.
Like most systems of measure there seems to be a basis, a standard or form, from which subsequent units, lengths in this case, are derived. The seked (probably better to call it ‘seqed’) was and is one of those ancient Egyptian units of measure that was much later called the cubit – I’m guessing that ‘cubit’ comes from a translation of ancient textual art or hieroglyphs and Coptic Egyptian. By the way, I’m not a linguist, either, but one comes across these things while checking into work from folks like Graham, Robert, John, Richard, and many others whose interests I share. One must remember that Coptic Egyptian and Egyptian Hieroglyphs were pretty much a mystery until that Rosetta stone breakthrough in recent history.
Again, I’m guessing, the ‘Royal’ attached to the royal cubit, is likely to render respect for the head-of-state or ruler, for instance, the length of the royal’s forearm, otherwise a length of someone’s forearm, from elbow to finger tip could vary widely, especially, when building with proportion in mind and accurately measuring celestial points consistently over a period of time. Probably why the ‘metre’ remains a significant unit if not stable frame of reference where measuring lengths are concerned today. It does away with anatomical fluctuations.
Aside from translations into Greek, Latin, and other languages for cubit, “seqed” seems more from the local region of Egypt – The ancients – who passed it along to the more recent inhabitants of Kemet. Kemet, of course, the ancient native name of Egypt. This reference to some time line would place the term cubit of recent translation and 'Seqed' origin prior to the building of the Pyramids themselves, since one need a frame of reference from which to measure to start.
The use of arm, hand, finger, and other anatomical portions of the human form are also well used and frequently seen in the Egyptian textual art – hieroglyphs. The pyramidal shape, I’m guessing, is also a natural form used. I once read somewhere, it was a while ago anyway, . . that if one was to fill a container with sand, part of which is crystallized quarts, allow for a small opening for the sand to trickle out onto a pile, look and measure from the side of that pile of sand, one would get something of a figure of a pyramid from a side view that closely resembles the sloping measure of the Pyramids. That same pile would give you a circumference to measure, and the point – top most – would give you the centre – a point of reference for the other forms one can later derive. I haven’t tested that hypothesis, but often wondered whether the angles and other parts measurable were natural angle and form references an ancient engineer might have used for their constants and stability as it seems to conform with the natural forces of the planet – one being gravity, for instance. The Pyramids certainly have some stability incorporated into them. I think so, anyway. . . Not sure if I helped you with an answer, but thanks for the question M J Thomas. .