The correct option is B cos(−π4)+isin(−π4),cos(3π4)+isin(3π4)
Let x=√−1=(−1)1/2
x=[cos(−π2)+isin(−π2)]1/2
x=[cos(2nπ−−π2)+isin(2nπ−π2)]1/2,n=0,1
x=[cos(4n−1)π2+isin(4n−1)π2]1/2,n=0,1
x=cos(4n−1)π4+isin(4n−1)π4,n=0,1
x=cos(−π4)+isin(−π4),cos(3π4)+isin(3π4)