$(a)\;\sqrt{2}\;[cos (\large\frac{\pi}{4})+i \;sin(\large\frac{\pi}{4})]\qquad(b)\;\sqrt{2}\;[cos (\large\frac{3\pi}{4})+i \;sin(\large\frac{3\pi}{4})]\qquad(c)\;\sqrt{2}\;[cos (\large\frac{5\pi}{4})+i \;sin(\large\frac{5\pi}{4})]\qquad(d)\;0$
