JEE 2023 — Mathematics PYQ

Let Q(α, β, γ) be the image of point p about the plane 2x - y + z = 9
$$\Rightarrow \frac{\alpha -1}{2}=\frac{\beta -2}{-1}=\frac{\gamma -3}{1}=\frac{-2(2-2+3-9)}{6}$$
$$<br>\Rightarrow \alpha =5,\beta =0,\gamma =5$$
area of ΔPQR is $\frac{1}{2}|\overrightarrow{PQ}\times \overrightarrow{PR}|$
$$=|-12\hat{i}-3\hat{j}+2\hat{k}|$$
$$<br>=\sqrt{594}$$