Let $\tan \alpha, \tan \beta$ and $\tan \gamma, \alpha, \beta, \gamma \neq \frac{(2 \mathrm{n}-1) \pi}{2}, \mathrm{n} \in \mathrm{N}$ be the slopes of three line segments, $\mathrm{OA}, \mathrm{OB}$ and OC , respectively, where O is origin. If circumcentre of $\Delta \mathrm{ABC}$ coincides with origin and its orthocentre lies on $y$-axis, then the value of $\left(\frac{\cos 3 \alpha+\cos 3 \beta+\cos 3 \gamma}{\cos \alpha \cos \beta \cos \gamma}\right)^2$ is equal to :