For every teenager who ever says "what will I even need math for?":
I have little hobby projects. One is building a "roundel" wall like the interior of the classic Dr. Who TARDIS of the 60s & 70s. And since I'm cheap, I want to build it as economically as possible.
The obvious, simple, way is to get a material like a sheet of styrofoam and cut holes in it in a honeycomb pattern and then put some kind of translucent inserts in the holes. But to do that, you wind up wasting more material than you use. My alternative is to cut a bunch of (essentially) "Y's" out of the styrofoam and then fasten them together at their ends so they form the circles. Then you stretch a sheet of 6mil plastic over the back, do some finish work to hide the seams and you've got a TARDIS wall pretty economically.
Right now I should be exercising but I'm fat and old and weak so I'm taking a rest break and tackling the problem of planning this project. First I opened a draw program and made 3 circles, nudged them around with x & y coordinates until they were in the right places and then stuck in the dividers to create my "Y" shapes. The problem then being that I don't have actual "Y" shapes; I can't copy/paste to lay a bunch of them out on the page unless I remember how to join points or "trace" over the thing. So screw it, keep it simple. Paper and pencil. 1"=1'. The roundels are 27" across, so I need 2.7" circles. Then I get my "Y" triangles and I just need to measure and duplicate them. My first problem came from not being able to find my compass. So I hunted up a selection of glasses and ramekins that looked about the right size and found one close enough. But I'm still no closer. I can measure the dimensions of the shapes. I can use Pythagorean theorem to extrapolate other measurements, but the curved edges screw that up (and the flattened ends, now that I think about it) so I've got to monkey with pi and circumference/arc calculations.
Or I can just draw a full sized template, cut out the shape I need and then draw that onto my styrofoam. I guess in the end, "what do I even need math for?".