Rewrite with only sin x and cos x. cos 3x

Step-by-step explanation:

Then using the identity for the cosine of a sum:

Then using the identities for the double angle which state that: and that , our problem becomes:

Then distributing:

Then combining like terms:

This is already in terms of cos(x) and sin(x) alone so we can stop.

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step-by-step explanation:

step-by-step explanation:

i have done this all on a piece of paper but idk how to put it on here cuz it needs to be drawn