There is a legendary diagram of spherical Earth from flat-Earthers that was made using AutoCAD involving the Pythagorean theorem, flaunting the fact that it is was created “using AutoCAD 2016 with 15-digit precision”™. The diagram is not wrong, but it does not account for the height of the observer and atmospheric refraction. And therefore, it is unsuitable for determining the obstruction of a distant object due to Earth’s curvature.
The numbers in the diagram will give us a much higher number than it should be. If a distant object is visible, but according to the diagram it should not, then flat-Earthers will incorrectly conclude that the Earth is flat.
Any calculation about the visibility of a distant object needs to account for the height of the observer and atmospheric refraction. The AutoCAD diagram does not account for both factors, and therefore cannot be used to determine the visibility of a distant object.
AutoCAD is a very popular computer-aided design software. But just like any other software, its output depends on the input. If the input is garbage, then the output will be garbage as well (GIGO = garbage in, garbage out).
It does not matter if AutoCAD has 15-digits precision. If the geometry is incorrect, then the results will be erroneous. In this case, the flat-Earthers merely hijack the reputation of AutoCAD and present the situation as if the software AutoCAD itself “proves a flat Earth.”