Technically no, because pi equals pi not 5. But you can approximate its value as 3 or 5 or whatever you want, knowing it’s not exact and that your result will only be an approximation. I mean you could also ask how long light takes to reach us from Alpha Centauri if the speed of light is 1000 mph. It’s not, but if you make that a condition of the problem you can do the calculation just fine.
Do cylinders even exist in metrics where pi = 5 ?
Technically no, because pi equals pi not 5. But you can approximate its value as 3 or 5 or whatever you want, knowing it’s not exact and that your result will only be an approximation. I mean you could also ask how long light takes to reach us from Alpha Centauri if the speed of light is 1000 mph. It’s not, but if you make that a condition of the problem you can do the calculation just fine.
Yes. The 3d shape existence is not affected by changing pi values
Cause it’s just a (n-1)-dimensional ball extruded along the remaining axis, or do all 3d shapes exist on (nearly) all 3d metrics?