MathNet 2022-part-04 — 197 problems (EN–VI) Question 26

$ABCD$ is a rectangle with side lengths $AB = CD = 1$ and $BC = DA = 2$. Let $M$ be the midpoint of $AD$. Point $P$ lies on the opposite side of line $MB$ to $A$, such that triangle $MBP$ is equilateral. Find the value of $\angle PCB$.