The value of the determinant
$Δ=\begin{vmatrix}cos(\alpha + \beta) & -sin(\alpha + \beta) & cos 2 \beta \\sin \alpha & cos \alpha & sin \beta \\-cos \alpha & sin \alpha & -cos \beta \end{vmatrix},$ is
Answer & explanation
Correct answer: option 4
The correct answer is option (4) : 0
Applying $R_1→R_1+(sin \beta ) R_2 + (cos \beta ) R_3 ,$ we get
$Δ=\begin{vmatrix}0 & 0 & 0 \\sin \alpha & cos \alpha & sin \beta \\-cos \alpha & sin \alpha & -cos \beta \end{vmatrix}=0$