Question

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Answer 1

this is incomplete question

Answer 2

Use the sum formula ,

$\cos 2B+\cos 2A=2\cos(A+B) \cos(A-B}) \\ \cos 2B-\cos 2A=2\sin(A+B) \sin(A-B)$

Thus,

$\frac{\cos 2B+\cos 2A}{\cos 2B-\cos 2A} =\frac{2\cos(A+B) \cos(A-B)}{2\sin(A+B) \sin(A-B) } \\ \frac{\cos 2B+\cos 2A}{\cos 2B-\cos 2A}=\tan(A+B) \tan(A-B)$

Answer.