My Pre-Cal teacher gave us this problem today. I have worked on it for a very long time and have goten no where . I was wondering if anyone had any ideas on how to do it, or even where to start. I started it myself with using the pythagorean idenities for the left side, then the difference of square; however after that I didn't know where to go.(adsbygoogle = window.adsbygoogle || []).push({});

cos²5x - cos²x = -sin4x x sin6x

Thanks a lot for your help,

Edit: (Damit... sorry I think I posted this in the wrong place)

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# Verifying a Hard Trigonometric Identitiy (please help)

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