Verify expression (4), Sec. 32, for log(z1/z2) by
(a) Using the fact that arg(z1/z2) = arg z1 − arg z2 (Sec. 8);
(b) Showing that log(1/z) = −logz (z ≠ 0), in the sense that log(1/z) and −log z have the same set of values, and then referring to expression (1), Sec. 32, for log(z1z2).