The three Giza pyramid base centers define a triangle and this defines a circle that encloses this triangle – mentioned before – but also an incircle meaning a circle which is enclosed in the triangle – touches the triangle in three points. Below I compute the dimensions of this circle:

All measures are from Petrie’s survey.

x = G1 to G2 = 486.877498896706 meters
y = G2 to G3 = 453.976464719914 meters
z = G1 to G3 = 936.157948894095 meters

t = (x+y+z)/2 = 938.506 meters

Khufu pyramid base length= 230.34752 meters

Radius of incircle = sqrt{[(t-x)*(t-y)*(t-z)]/t} = 23.337 meters

diameter of incircle = 2 x 23.337 meters = 46.675 meters =
= (440/230.34752) x 46.675 royal cubits = 89.156 royal cubits

Hetepheres I's Pyramid - G1a base length = 45.5 x 47.4 x 46.5 x 45.7 m (mean = 46.275 m)

Henutsen's Pyramid - G1c base length = 45.5 x 46.7 x 46.8 x 45.2 m (mean = 46.05 m)

Khufu knew the whole Giza plan, since he chose for his subsidiary pyramids – mainly the two on the edge – dimensions that enclosed the incircle created by the three Giza pyramids – which were not all constructed yet – his own pyramid was the one only one erected – a point on a plain.