4. Show that the matrix $$A = \begin{bmatrix} 2\sin^2 \alpha & 2\sin^2 \beta & 2\sin^2 \gamma \\ 3\cos^2 \alpha & 3\cos^2 \beta & 3\cos^2 \gamma \\ 1 & 1 & 1 \end{bmatrix}$$ is not invertible for any value $$\alpha, \beta, \gamma$$.