Kanga: “In my view the base is 201.6 cubits and the slope is 5:4. This creates a whole cubit height of 126 cubits, the same as the height of the 154c level pyramid within Khufu's pyramid. Also the 154c elevation in Khufu's pyramid is used as the base length for Niuserre's pyramid.”

If true, it means the master builders were very much aware of the designs of previous pyramids and were using the same design ‘rules’ that would inevitably mean similar proportions.

M&R thought that due to the lack of certainty for the exact length of the sides, 200 cubits was the most likely length. (Maragioglio & Rinaldi, Part 6, 1967: 96)
Petrie's survey estimates the length of a side of Menkaura's pyramid as 105.5m (201.5 cubits), but thought it seems most probable “….that it was designed to be 200 cubits long; for the length of the cubit required, 20.768 (527.5mm), is far within the variations of the cubit of the Granite Chamber, and other parts inside. The first design of the Pyramid, before its expansion, appears to have been a base of 100 cubits, like some of the small Pyramids. The angle of 51º 0', or more likely 51º 10', may be designed by a rise of 5 on a base of 4 (5:4), which would produce 51º 20’ (51.34º); but the whole of this Pyramid, inside and outside, is so far less accurate than the two larger, that no refinement of work or of design need be looked for.” (Petrie 1883: 204)

One reason for the uncertainty, apart from the fact that we are dealing with a ruin, is that its not known for certain if the casing was resting on a ‘pavement’, or if “the face was intended, when finished, to end in a vertical foot and this would be covered by the pavement to be afterwards added.” (Petrie)

If a designed base of 200 x 200 cubits was intended as M&R and Petrie believed, the height according to the angle of incline is:

5:4 (51.34º) h = 125 cubits
sqd 5 1/2 (51.843º) h = 127.27 cubits (sqd 5 1/2 is is consistent with Khufu’s pyramid)
sqd 5 3/4 (50.6º) h = 121.74 cubits

200 cubits is consistent with other examples of structures from this period:

Height of each of Snefru’s dual pyramids - 200 cubits. Mastaba 17 at Maidum - 200 x 100 cubits.

Textual examples from the Old Kingdom, show that in these examples at least, designers specified measurements in whole numbers and multiples of 10, 100, 1000 cubits for primary large measurements used in architectural design. A walled estate of Metjen, a high official who died in the reign of Khufu's father, Snefru - 200 x 200 cubits. The plan of the Dynasty 4 tomb of Debehen was designed with specified measurements of 100 x 50 cubits.  A text from the Dynasty 5 Sun Temple of Niuserra mentions a stone structure with a length of 7000 cubits (Strudwick 2005: 90).  The ground plan for Izezi's Dynasty 5 Sed festival enclosure was 1000 x 440 cubits (Strudwick 2005: 313) (1000 cubits is half the length of the 'Giza dual diagonals' and 440 cubits is the length of a base side of Khufu's pyramid).

Based on these examples, it seems doubtful they would choose 201.6 x 201.6 cubits for the base, unless it was intended to create “…a whole cubit height of 126 cubits, the same as the height of the 154c level pyramid within Khufu's pyramid”.

Chris