1)[tex]cos(\frac{3\pi}{4}) = cos(\pi - \frac{\pi}{4}) = -cos(\frac{\pi}{4}) = -\frac{\sqrt2}{2}\\sin(\frac{3\pi}{4}) = sin(\pi - \frac{\pi}{4}) = sin(\frac{\pi}{4}) = \frac{\sqrt2}{2}[/tex] . Donc [tex]z = -2\sqrt 2 + i2\sqrt2[/tex]
2) [tex]z = 2(cos(-\frac{\pi}{6}) + isin(\frac{\pi}{6})) = 2(cos(\frac{\pi}{6}) - isin(\frac{\pi}{6}))[/tex]. Donc [tex]z = \sqrt3 - i[/tex]
3) [tex]z = \sqrt2(cos(\frac{\pi}{2}) + isin(\frac{\pi}{2}) = \sqrt2(0 + i\times1) = i\sqrt2[/tex] .
