Q. If $f(x)=\begin{vmatrix}\cos (x+\alpha) & \cos (x+\beta) & \cos (x+\gamma) \\ \sin (x+\alpha) & \sin (x+\beta) & \sin (x+\gamma) \\ \sin (\beta-\gamma) & \sin (\gamma-\alpha) & \sin (\alpha-\beta)\end{vmatrix}$ and $f(0)=-2$ then $\displaystyle\sum_{ r =1}^{30}|f(r)|$ equals
Determinants
Solution: