Express product as a sum/different containing only sines or cosines.

sin4Asin2A=????

I stuck at beginning.

THX WHO HELP~!

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- September 11th 2008, 05:52 AMsanikuitrigo sum/different~do not do~!
Express product as a sum/different containing only sines or cosines.

sin4Asin2A=????

I stuck at beginning.

THX WHO HELP~! - September 11th 2008, 06:07 AMthelostchild
remember that

(so obviously )

and

make substitutions and simplify :) - September 11th 2008, 06:08 AMmr fantastic
See my reply in this thread for the formulae you need: http://www.mathhelpforum.com/math-he...dentities.html

- September 11th 2008, 06:20 AMMr.Greenanswer
sin4Asin2A=sin2(2A)sin2A

=2sin2Acos2Asin2A

=2(2sinAcosA)(1-2sin^2A)(2sinAcosA)

=8sin^2Acos^2A(1-2sin^2A)

=8sin^2A(1-sin^2A)(1-2sin^2A) - September 11th 2008, 06:34 AMmr fantastic
- September 11th 2008, 07:43 AMsanikui
I got it from Mr.fantastic.

THx Mr.Green ans Mr.fantastic~!!

I'm continues do my homework~!!(Happy)