Here's one I came across on Facebook the other day. I had no recollection of it from school, but it's pretty neat and it appeared in someone's cheat sheet of st

Here's one I came across on Facebook the other day. I had no recollection of it from school, but it's pretty neat and it appeared in someone's cheat sheet of standard trig formulas with double angles and all that familiar stuff. https://en.wikipedia.org/wiki/Mollweide%27s_formula?wprov=sfla1 https://en.wikipedia.org/wiki/Mollweide%27s_formula?wprov=sf...