Well, to get the height or steepness of a pyramid right is mathematical, no doubt. But to build a square base, which the opening of the article appears to refer to, is very simple. (Says I, recalling how I squared off a woodshed I built a couple of years ago.)
First, all the sides are the same length, so measure them off. Then measure the two diagonals from opposite corners. If the sides are all equal, then you have a square, not a rectangle, and if the diagonals are equal, then you have perfect right angles. Simple as that.
And, if you’re building a woodshed, you can either use a plumb bob or a bubble level, or measure the diagonals of each side, to get those square.
...therefore...the Great Pyramid started out as a woodshed...and the project went totally out of control!