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JEE Math Practice Question

A value of $$\theta \in \left( {0,{\pi \over 3}} \right)$$, for which $$\left| {\begin{matrix} {1 + {{\cos }^2}\theta } & {{{\sin }^2}\theta } & {4\cos 6\theta } \\ {{{\cos }^2}\theta } & {1 + {{\sin }^2}\theta } & {4\cos 6\theta } \\ {{{\cos }^2}\theta } & {{{\sin }^2}\theta } & {1 + 4\cos 6\theta } \\ \end{matrix} } \right| = 0$$, is :

  1. A.$${\pi \over {18}}$$
  2. B.$${\pi \over {9}}$$
  3. C.$${{7\pi } \over {24}}$$
  4. D.$${{7\pi } \over {36}}$$

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