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November 28, 2014

Homework Help: pre-calculus

Posted by Luis on Sunday, May 13, 2012 at 5:04pm.

Currently in school we're learning about proving identities and for extra credit I got this problem.

cosB= -8/17 in quad II and I have to find sin 7B.

I have gotten this far:

sin7B= sin(3B+4B)
sin3Bcos4B+sin4Bcos3B

my problem I can't figure out how to further break it down. After that I can do the rest.

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