SOLUTION: How do you prove that {{{cos(5x) = 5 cos(x) - 20 cos^3(x) + 16 cos^5(x)}}} using sum and difference identities? Thank you :D
*EDIT: I'm so sorry, cos^5 x should be cos 5x
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-> SOLUTION: How do you prove that {{{cos(5x) = 5 cos(x) - 20 cos^3(x) + 16 cos^5(x)}}} using sum and difference identities? Thank you :D
*EDIT: I'm so sorry, cos^5 x should be cos 5x
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Question 604252: How do you prove that using sum and difference identities? Thank you :D
*EDIT: I'm so sorry, cos^5 x should be cos 5x Found 2 solutions by jsmallt9, jjvseg:Answer by jsmallt9(3758) (Show Source):
What you posted was:
This is not an identity. This equation is only true for certain values of x, not all values of x.; and
All the arguments are x. There is no need to use sum and/or difference identities to manipulate the arguments.
If you re-post the question, then I wonder if the double angle and half angle identities would be considered "sum and difference identities"? I ask because I suspect that they might be very helpful.
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