Math
\(
\def \l {\left}
\def \r {\right}
\def \f {\frac}
\def \b#1{\l(#1\r)}
\def \root [#1]#2{\sqrt[\leftroot{2}\uproot{2}\scriptstyle #1]{#2}}
\def \sroot [#1]#2{\sqrt[\large #1]{#2}}
\def \cbrt #1{\root[3]{#1}}
\def \scbrt #1{\sroot[3]{#1}}
\DeclareMathOperator{\acoth}{acoth}
\)
Note: Unlike the rest of the site, these math papers are licensed under CC BY-SA
Here are some papers documenting derivations for things I've found online. In other words, I didn't come up with the original idea for these:
Converting $ax^3+bx^2+cx+d$ to $t^3+pt+q$
Here are some things I've derived myself (but which many other people have probably derived before):
Show that $\sum\limits_{i=2}^n \acoth i = \f{1}{2} \ln \f{n(n+1)}{2}$
Denesting $\sqrt{x\pm\sqrt{y}}$
Find Other $\scbrt{a}$ from Known $\scbrt{a}$