Hi, got a problem that I need some help with.

How can I express cos 4x in cos x?

Help appreciated.

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- Jun 5th 2009, 02:31 AMBurger king[SOLVED] trig question
Hi, got a problem that I need some help with.

How can I express cos 4x in cos x?

Help appreciated. - Jun 5th 2009, 02:50 AMgreat_math

- Jun 5th 2009, 03:26 AMgreat_math
Another way:

- Jun 5th 2009, 03:34 AMBurger king
Great, the other one was a bit easier :) Does the answer satisfy the question in the sense that it requires the answer to be expressed in cosx, whereas the answer you calculated has a + 1 term?

- Jun 5th 2009, 03:37 AMgreat_math
1 is a constant so it does satisfy the question

- Jun 5th 2009, 03:43 AMgreat_math

This can also be written as