Can anyone help me prove this trig identity: Cos(4ά)+4cos(2ά)+3=8cos(4ά) Thanks
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I think the identity is right?
Yes, thats right. Sorry...
Ok. So what ideas have you had so far?
Thats what I did...I try everything...still nothing
You missed some squares in there.
2. In your expression, you still have a in there. Reduce the angle, and see what you get.
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