Hi all, this is my first post here, i need some help proving this identity (sinAsin2A +sin3Asin6A)/(sinAcis2A+sin3Acos6A) =tan5A Thanks
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Use these formulas: And the right hand member must be
Last edited by red_dog; July 1st 2009 at 11:11 PM.
You'll have to use the product-to-sum formulas: AND So, Then, use the sum-to-product formulas: AND Hmm, I'm getting -tan 5A... 01 EDIT: posted too late. red dog also got -tan 5A.
In my book it DOES say that tan5A so i guess it would be a printing error because there is at least one other problem where the "-" sign is missing. but thanks anyway!
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