Question

If 5(tan²x – cos²x) = 2cos 2x + 9, then the value of cos 4x is :
(1) $- \frac{7}{9}$
(2) $- \frac{3}{5}$
(3) $\frac{1}{3}$
(4) $\frac{2}{9}$

Answer 1

Answer:

Step-by-step explanation:

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