Question

The value of the determinant $\left|\begin{array}{ccc}1& 0& 0\\ 2& \cos x& \sin x\\ 3& \sin x& \cos x\end{array}\right|$ is

• A. 1
• B. 0
• C. cos 2x
• D. sin 2x

Answer 1

Answer: (C)

The value of the given determinant $=1({\cos }^{2}x-{\sin }^{2}x)=\cos 2x$.