Oooo! Oooo! I know this! I know this!
Catenary and it's given by y = cosh(x). I learnt that when I was 16 and wanted to know what the hell cosh, sinh and tanh buttons did on my new calculator!
In 34 years of engineering, I cannot recall ever using a hypbolic trig function. Lots Euler and de Moivre's stuff but not hyp trigs.
I wrote a program to solve for equation roots using Newton's method on my TI59 programmable calculator when I was just 18.
Can I have a prize? Or at least a round of