If ${z_1}$ and ${z_2}$ are two complex numbers satisfying the equation $\left| \frac{z_1 +z_2}{z_1 - z_2} \right|=1$, then $\frac{{{z_1}}}{{{z_2}}}$ is a number which is
Positive real
Negative real
Zero or purely imaginary
None of these
Which of the following are correct for any two complex numbers ${z_1}$ and ${z_2}$
If $z_{1}=2-i, z_{2}=1+i,$ find $\left|\frac{z_{1}+z_{2}+1}{z_{1}-z_{2}+1}\right|$
${\left| {{z_1} + {z_2}} \right|^2} + {\left| {{z_1} - {z_2}} \right|^2}$ is equal to
$|{z_1} + {z_2}|\, = \,|{z_1}| + |{z_2}|$ is possible if
If $z$ is a complex number, then the minimum value of $|z| + |z - 1|$ is