If you multiply 0.5 by itself then you get a quater..... so a half squared is 1/4 .......so 1/4 square rooted is a +/- a half?

yet trying to do the inverse.....and square rooting a half = (1/2)^-1/2 is +/- 1/sqrt2

Can someone kill my silly thought process please as I am sleepy and not thinking right!