Prove that , for all values of a , sin a (cos 2a+cos 4a+cos 6a)=cos 4a sin 3a

i can prove this ..

Deduce that

i am not sure with this . i don see how i can use the prove above to solve this . Thanks for your help .

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- Aug 24th 2009, 08:47 PMthereddevilsdeduce
Prove that , for all values of a , sin a (cos 2a+cos 4a+cos 6a)=cos 4a sin 3a

i can prove this ..

Deduce that

i am not sure with this . i don see how i can use the prove above to solve this . Thanks for your help . - Aug 24th 2009, 09:03 PMChris L T521