Power calculation and Ohm's Law for Reactance
i would like to know why doesn't the above work?


It's not \$\angle{60}\$, it's \$\angle{-60}\$ as the denominator: -



The supply voltage can be regarded as at 0 degrees and the current is lagging 60 degrees behind at 300 degrees. Hence the angle of the current is 300 degrees or -60. See this website which also shows this picture: -