I was recently sent a link to:
Which has a host of pdf files with detailed instructions on all manner of geometric calculations. The focus of the site is animation for games programs, but there is plenty here of interest to engineers.
A small part of their listing is shown below (click for full size view):
 | dougaj4 on 3D plots with the latest … |
| 3D plots with the la… on 3D Matplotlib Plots in Ex… | |
| Suelio Josileissu on 3D plots with the latest … | |
| Installing Python an… on SectionProperties update 3 | |
| Dan & naD | Newt… on The Daily Mail Song | |
| dougaj4 on ULS Design Functions 2.13 |
 | Alvin on ULS Design Functions 2.13 |
 | Larry Schuster on Microsoft blocking VBA in down… |
| dougaj4 on Downloads |
 | Sunny on Downloads |
| dougaj4 on Section Properties with MeshPY… |
 | Alex on Section Properties with MeshPY… |
| Alex on Section Properties with MeshPY… |
| Installing PyPardiso… on Installing PyPardiso and speed… | |
| Installing PyPardiso… on Making Finite Element Analysis… |
Newton Excel Bach, not (just) an Excel Blog 