$|{z_1} + {z_2}|\, = \,|{z_1}| + |{z_2}|$ is possible if
${z_2} = {\overline z _1}$
${z_2} = \frac{1}{{{z_1}}}$
$arg\,({z_1}) = arg ({z_2})$
$|{z_1}|\, = \,|{z_2}|$
If ${z_1}.{z_2}........{z_n} = z,$ then $arg\,{z_1} + arg\,{z_2} + ....$+$arg\,{z_n}$ and $arg$$z$ differ by a
Let ${z_1}$ and ${z_2}$ be two complex numbers with $\alpha $ and $\beta $ as their principal arguments such that $\alpha + \beta > \pi ,$ then principal $arg\,({z_1}\,{z_2})$ is given by
If $z = 3 + 5i,\,\,{\rm{then }}\,{z^3} + \bar z + 198 = $
If $|z - 25i| \le 15$, then $|\max .amp(z) - \min .amp(z)| = $
If $0 < amp{\rm{ (z)}} < \pi {\rm{,}}$then $amp(z)-amp ( - z) = $