| 16 | = ·761904 = Tan. < ADC | = 37° 18′ 14 | 16″ |
| 21 | 46 | ||
| ∴ < DAC | = 52° 41′ 45 | 30″ | |
| 46 |
but as it is probable that the pyramid was built to the ratio of 33 to 20, I have marked the base angle in Fig. 17, as 52° 41′ 41″.
I took Cheops out, first as a Π pyramid, and made his lines to a base of 420 cubits, as follows—
| Half-base | 210 |
| Altitude | 267·380304 |
| Apothem | 339·988573 (See Fig. 73.) |
(Cheops) Fig. 73.
But to produce the building ratio of 34 to 21, as per diagram Figure 6 or 9, I had to alter it to—
| Half-base | 210 |
| Altitude | 267·394839 |
| Apothem | 340 |
Thus the theoretical angle of Cheops is 51° 51′ 14·3″, and the probable angle at which it was built, is 51° 51′ 20″, as per figure 15.
Cheops is therefore the mean or centre of a system—the slopes of Mycerinus being a little flatter, and those of Cephren a little steeper, Cheops coming fairly between the two, within about 10 minutes; and thus the connection between the ground plan of the group and the slopes of the three pyramids is exactly as one might expect after examination of Figure 3, 4 or 5.