Mathematics

Problem

z_1, z_2

and

z_3, z_4

are two pairs of conjugate complex numbers, then

\arg\left(\frac{z_1}{z_4}\right) + \arg\left(\frac{z_2}{z_3}\right)

equals to a. 0 b.

\frac{\pi}{2}

\pi

\frac{3\pi}{2}