B 4/root 2
we could do both ways, find either the adjacent or opposite side.
opposite :
sin(45) = opposite/hypotenuse
opposite = 2 root 2 (basically equals to B but just not in the same form)
adjacent :
cos(45) = adjacent/hypotenuse
adjacent = 2 root 2
so both are the same, just two different ways to get to it.