Can Euler's Formula Simplify Trigonometric Proofs?

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SUMMARY

The discussion focuses on using Euler's formula to simplify trigonometric proofs, specifically the equation (2sin^4x(2cos^2x+1))/3 = [sin^2(2x)/6-1/3][cos(2x)]. A participant attempts to manipulate the right side by substituting cos(2x) with 1 - 2sin^2x, leading to a complex expression. The suggestion to apply Euler's formula, e^{4 i \theta} = (e^{i \theta})^4, is presented as a potential method to advance the proof. The conversation highlights the challenges in notation and clarity when dealing with trigonometric identities.

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Hi. I am trying to prove that (2sin^4x(2cos^2x+1))/3 = [sin^2(2x)/6-1/3][cos(2x)].

I tried fixing the right side, changing cos2x to 1 - 2sin^2x, and I went all the way to

(4sin^2x-4sin^4x-2-8sin^4x+8sin^6x+4sin^2x)/6.

I am clueless on how to continue the proof. Please help. Thanks.
 
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Your notation isn't very clear but I think this may help:

e^{4 i \theta} = \left( e^{i \theta} \right)^4

and apply Euler's formula to the individual exponentials.
 

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