Half-base 210 Alt.i.tude 267394839 Apothem 340
Thus the theoretical angle of Cheops is 51 51" 143?, 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.