If $5\left(\tan ^{2} x-\cos ^{2} x\right)=2 \cos 2 x+9$, then the value of $\cos 4 x$ is :-
$-\frac{7}{9}$
$-\frac{3}{5}$
$\frac{1}{3}$
$\frac{2}{9}$
Correct Option: 1
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