“If you add 180° to 30° you get 210° which is 30° W longitude and not 10° 54’, but I take your point.”
Well, 180 degrees would be half the circumference, not half the diameter. The diameter is 2r, and the circumference is 2r*Pi. So divide 180 degrees by Pi and you get the actual number of degrees that corresponds to half the diameter of the Earth (appr. 57.296 degrees).
OK, I accept your calculations but can’t see why half the diameter of the earth expressed in degrees is relevant the positions of the pyramids in question. I do not grasp the geometrical relation to the pyramids.
My numbers were intended to show that caral was not halfway round from Giza