If z = x+iy, |z+1| = |z−1| and arg ⟮z−1z+1⟯ = π4, then z =
|z+1| = |z−1|
⇒(x+1)2+y2 = (x−1)2+y2⇒x = 0
Then z−1z+1 = iy−1iy+1 = (iy−1)(−iy+1)1+y2 = y2−1+2yiy2+1
arg ⟮z−1z+1⟯ = π4⇒y2−1 = 2y,y>0
⇒y = 1+√2
Hence z = (1+√2)i