For a non-zero complex number z , let arg ( z ) denote the principal argument with - π < a r g z…

For a non-zero complex number z, let arg(z) denote the principal argument with -π<argzπ then, which of the following statement(s) is (are) FALSE?
  1. Arg-1-i=π4, where i=-1
  2. The function f:R-π,π defined by ft=arg-1+it for all tR , is continuous at all points of R, where i=-1
  3. For any two non-zero complex numbers z1 and  z2 , arg z1z2-argz1+arg z2 is an integer multiple of 2π
  4. For any three given distinct complex numbers z1,  z2 and  z3 , the locus of the point z satisfying the condition argz-z1z2-z3z-z3z2-z1=π lies on a straight line

Solution

A Arg-1-i=-3π4
B Arg-1+it=π-tan-1t,t0-π+tan-1t,t<0 
Discontinuous at t=0
(C) argz1z2-argz1+argz2
=  argz1-argz2-argz1+arg z2=0
D argz-z1z2-z3z-z3z2-z1=π
  z-z1z2-z3z-z3z2-z1 is real
  z, z1, z2, z3 are concyclic

Asked in: JEE Advanced 2018 (Paper 1)

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