If z1 and z2 are two complex numbers such that |z1|=|z2| and (z)+arg (z2)=π, then show that z1=−¯z2.
|z1|=|z2|Let arg(z1)=θ∴ arg (z2)=π−θIn polar form, z1=|z1| (cos θ+i sin θ) ....(i)z2=|z1| (cos (π−θ)+i sin (π−θ))=|z2| (−cos θ+i sin θ)=−|z2| (cos θ−i sin θ)Finding conjuage of ¯¯¯¯¯z2=−|z2| (cos θ+i sin θ) ...(ii)(i)∖(ii) is equal to z1¯¯¯¯z2=−|z1|(cos θ+i sin θ)|z2|(cos θ+i sin θ)z1¯¯¯¯z2=−|z1||z2| [∵ |z1|=|z2|]z1¯¯¯¯z2=−1z1=−¯¯¯¯¯z2
Hence proved.