Do people really use this or any other of the cheatsheets you find online?
In my experience, any cheat sheet that I didn't make myself is useless to me. Going directly to the sheet without having done the synthesis of information yourself skips the most important part of the process.
These cheetsheets aren't meant to be printed off and carried into your open book tests. They are meant to be greppable formula lookups. They're useful if you can define the problem but don't know the equation off your head to solve it. Think something like differentiating a trig function after you haven't used it in a while or looking up some statistical approximation.
Pretty much anything is easier to reference than a man page :) I wish the standard for man, would be to include examples. But maybe I'm in the minority of people who learn by example.
Math cheatsheet made by others are not very useful. When it's not about a large public API it doesn't really make sense. People also forget that most theorems/formulas have slight modifications that are very useful but make these kind of enterprise very difficult.
In my experience, any cheat sheet that I didn't make myself is useless to me. Going directly to the sheet without having done the synthesis of information yourself skips the most important part of the process.