Let for a triangle A B C, AB =-2 i + j +3 k; CB =α i +β j +γ k; CA =4 i +3 j +δ k If δ>0 and the area of the triangle ABC is 5 √ 6, then C B · C A is…

Let for a triangle $\displaystyle A B C$, $$\begin{aligned} & \overrightarrow{\mathrm{AB}}=-2 \hat{i}+\hat{j}+3 \hat{k} \\ & \overrightarrow{\mathrm{CB}}=\alpha \hat{i}+\beta \hat{j}+\gamma \hat{k} \\ & \overrightarrow{\mathrm{CA}}=4 \hat{i}+3 \hat{j}+\delta \hat{k} \end{aligned} $$ If $\displaystyle \delta>0$ and the area of the triangle ABC is $\displaystyle 5 \sqrt{6}$, then $\displaystyle \overrightarrow{C B} \cdot \overrightarrow{C A}$ is equal to