Square roots of $-i$,where $i=\sqrt{-1}$, are
- $i,-i \\$
- $\cos(-\dfrac{\pi }{4} )+i\sin(-\dfrac{\pi }{4})+\cos(\dfrac{3\pi }{4})+i\sin(\dfrac{3\pi }{4}) \\$
- $\cos(\dfrac{\pi }{4} )+i\sin(\dfrac{3\pi }{4})+\cos(\dfrac{3\pi }{4})+i\sin(\dfrac{\pi }{4}) \\$
- $\cos(\dfrac{3\pi }{4} )+i\sin(-\dfrac{3\pi }{4})+\cos(-\dfrac{3\pi }{4})+i\sin(\dfrac{3\pi }{4})$