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herz · Mar 20, 2008, 07:15 AM

I am learning to verify trig identities and have no iea how to get started on this one.

2 sin^2 2x + cos4x = 1

If anyone can help get me started... Thank you

galactus · Mar 20, 2008, 09:05 AM

Take note of the identity: $cos(2u)=1-2sin^{2}(u)$

Then, $cos(4x)=1-2sin^{2}(2x)$

herz · Mar 20, 2008, 10:29 AM

Wow I got it! Thank you, I had not used that identity before. It wasn't on my list of ID's but searched and found them. Thank you for the help!