[math-fun] names for some well known facts

in probability theory: variance + mean^2 = meansquare in minimization: Let F(x1,x2,x3,...,xN) be a concave-U symmetric function of N variables. Then its min necessarily occurs when all the variables are equal. The above are two well known theorems. What I want to know is, do they have names, or cites, or something like that so I do not have to re-prove them myself, I can just name/cite them? There was once a sci-fi book with title "True names" postulating that once I know your true name, I have great power...