1.
Let A={z∈C:1<∣z−(1+i)∣<2}A = \{z \in \mathbb{C} : 1 < |z - (1 + i)| < 2\} and B={z∈A:∣z−(1−i)∣=1}B = \{z \in A : |z - (1 - i)| = 1\}. Then, BB: