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## Homework Statement

Write the Trigonometric Expression as an algebraic expression.

cos(2arccos 2x)

## Homework Equations

Probably the inverse properties, I'm not sure.

## 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.