$$\begin{aligned} &\begin{aligned} & \frac{x-3}{7}=\frac{y-2}{-1}=\frac{z+1}{-2}=\lambda \\ & \Rightarrow 7 \lambda+3,-\lambda+2,-2 \lambda-1 \\ & \text { dr's of QP } \Rightarrow \\ & 7 \lambda-7,-\lambda+5,-2 \lambda \end{aligned}\\ &\text { Now }\\ &\begin{aligned} & (7 \lambda-7) \cdot 7-(-\lambda+5)+(2 \lambda) \cdot 2=0 \\ & 54 \lambda-54=0 \Rightarrow \lambda=1 \\ & \therefore \mathrm{P}=(10,1,-3) \\ & \overrightarrow{\mathrm{PQ}}=-4 \hat{\mathrm{j}}+2 \hat{\mathrm{k}} \\ & \overrightarrow{\mathrm{PR}}=-7 \hat{\mathrm{i}}-3 \hat{\mathrm{j}}+4 \hat{\mathrm{k}} \end{aligned} \end{aligned}$$

Area $$=\left| {{1 \over 2}\left| {\matrix{ i & j & k \cr 0 & { - 4} & 2 \cr { - 7} & { - 3} & 4 \cr } } \right|} \right| = 3\sqrt {30} $$