9pi /4
First, make you can make a good guess of what the missing point is by looking at the graph. (5,-2)
https://www.desmos.com/calculator
The you can see that a radius created here and the intersecting area is essentially an area of a sector, which (1/2) * (r^2) * the angle of the sector.
![](/img/upload/a761022d86e2558a76a1555a/ss.png)