If $|z - 25i| \le 15$, then $|\max .amp(z) - \min .amp(z)| = $
${\cos ^{ - 1}}\left( {\frac{3}{5}} \right)$
$\pi - 2{\cos ^{ - 1}}\left( {\frac{3}{5}} \right)$
$\frac{\pi }{2} + {\cos ^{ - 1}}\left( {\frac{3}{5}} \right)$
${\sin ^{ - 1}}\left( {\frac{3}{5}} \right) - {\cos ^{ - 1}}\left( {\frac{3}{5}} \right)$
Conjugate of $1 + i$ is
If $\frac{\pi }{2} < \alpha < \frac{3}{2}\pi $ , then the modulus and argument of $(1 + cos\, 2\alpha ) + i\, sin\, 2\alpha $ is respectively
If $\frac{{z - \alpha }}{{z + \alpha }}\left( {\alpha \in R} \right)$ is a purely imaginary number and $\left| z \right| = 2$, then a value of $\alpha $ is
The real value of $\theta$ for which the expression $\frac{{1 + i\,\cos \theta }}{{1 - 2i\cos \theta }}$ is a real number is $\left( {n \in I} \right)$
If ${z_1}$ and ${z_2}$ are two non-zero complex numbers such that $|{z_1} + {z_2}| = |{z_1}| + |{z_2}|,$then arg $({z_1}) - $arg $({z_2})$ is equal to