-1+i=√2[cos(3π/4)+isin(3π/4)]
(-1+i)^n=(√2)^n[cos(3nπ/4)+isin(3nπ/4)]
-1-i=√2[cos(5π/4)+isin(5π/4)]
(-1-i)^n=(√2)^n[cos(5nπ/4)+isin(5nπ/4)]