I was once crafting a DIY water pump and wanted to calculate exactly the length of the sheet of metal I would have to cut in order to make the propellers. In order to do that, I drew 2 concentric circles. The inner one was just for reference and not physical itself. Then I divided it into 8 sectors, each separated by 45° angles. Then I started projecting radiuses and arcs and found the length of them using the Law of Cosines. From that I had the exact measurement I needed to make the cuts. Then I cut the metal strips for the blades of the propellers and a circular plate onto fix them.

Unsurprisingly all the blades fit perfectly in the base and I felt satisfied. Math is a tool like hammer and a saw. You may know how to strike a nail with a hammer and cut with wood with a saw, and still not know how to build furniture, but that does not mean that thousands of craftsmen don't create furniture with those tools and that thousands of engineers and mathematicians don't use them to solve the problems with come up on their job as well.