(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Write the Trigonometric Expression as an algebraic expression.

cos(2arccos 2x)

2. Relevant equations

Probably the inverse properties, I'm not sure.

3. The attempt at a solution

I know I can rewrite this equation as.

u= arccos 2x

cos(2cos u=2x)

I can also say that the adjacent leg is 2x units long and the hypotenuse is 1 unit long. Then using the pythagorean theorm I can figure the opposite leg to be sqrt(1-4x^{2})

I'm not sure If this is necessary though can someone point me in the right direction? The 2 in front of the arccos is throwing me off because if that wasn't there I would just use the inverse property and cos(arccos 2x) would equal 2x.

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# Homework Help: Writing A Trig Expression as an Algebraic Expression

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