Problem 1524 (difficulty: 3/10)

Sketch the set of those complex number for which

(a) \(\displaystyle \displaystyle\frac{|z|}{\re z} < K\);  (b) \(\displaystyle |z-1|+|z+1| < 4\);  (c) \(\displaystyle \re\displaystyle\frac{1+z}{1-z}>0\).

Give me another random problem!