Question 604252
This cannot be correct because ...<ul><li>What you posted was:
{{{cos^5(x) = 5cos(x) - 20cos^3(x) + 16cos^5(x)}}}
This is not an identity. This equation is only true for certain values of x, not <i>all</i> values of x.; and</li><li>All the arguments are x. There is no need to use sum and/or difference identities to manipulate the arguments.</li></ul>
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.