let z₁, z₂ and z₃ be three distinct complex numbers , satisfying |z₁| = |z₂| = |z₃| = 1 . which of the following is /are true?
a. If arg (z₁/z₂) = π/2 then arg (z-z₁/z-z₂) > π/4 where |z| gt 1
b. |z₁z₂ + z₂z₃ + z₃z₁| = |z₁ + z₂ + z₃|
c. lim ((z₁ + z₂)(z₂ + z₃)(z₃ + z₁)/z₁.z₂.z₃) = 0
d. If |z₁ - z₂| = √2|z₁ - z₃| = √2|z₂ - z₃|, then Re (z₃ - z₁/z₃ - z₂) = 0