SEAMO 2027 - Paper C - SET 10 - Self-study Question 4

In the diagram, $\angle ADB=90^\circ$ and $C$ is the midpoint of arc $AB$. Given that shaded region $x$ has area $12\text{ cm}^2$, find the area of shaded region $y$, in $\text{cm}^2$.

Diagram convention used here: the outer arc is a quadrant centred at D, and the inner arc is a semicircle with diameter DB, as depicted.