Chứng minh \(\frac{\cos3\alpha+\cos\alpha}{\sin3\alpha+\sin\alpha}.\tan2\alpha-8\sin^2\alpha.\cos^2\alpha=\cos4\alpha\) với \(\alphae k\frac{\pi}{4}\left(k\in Z\right)\)
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Toán lớp 10
Chứng minh \(\frac{\cos3\alpha+\cos\alpha}{\sin3\alpha+\sin\alpha}.\tan2\alpha-8\sin^2\alpha.\cos^2\alpha=\cos4\alpha\) với \(\alphae k\frac{\pi}{4}\left(k\in Z\right)\)
