Question
If $P(x, y)$ denotes $z = x + i y$ in Argand's plane and $\left|\frac{z - 1}{z + 2}\right| = 1$, then the locus of $P$ is a/an __________.
If $P(x, y)$ denotes $z = x + i y$ in Argand's plane and $\left|\frac{z - 1}{z + 2}\right| = 1$, then the locus of $P$ is a/an __________.