simplify the expression:

cos(2arctanx)

would the answer be 2x/sqrt(x^{2}+1)?

im not really sure if im heading in the right direction or not....

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- Oct 1st 2012, 05:16 PMpnfullerhelp simplify the expression
simplify the expression:

cos(2arctanx)

would the answer be 2x/sqrt(x^{2}+1)?

im not really sure if im heading in the right direction or not.... - Oct 1st 2012, 05:52 PMpickslidesRe: help simplify the expression
I think you are on the right track

simplify cos(2*arctan(x)) - Wolfram|Alpha - Oct 1st 2012, 06:01 PMHallsofIvyRe: help simplify the expression

And, if , then .

We can represent that by a right triangle having angle , "opposite side" x, and "near side" 1. By the Pythagorean theorem the hypotenuse has length . So what are and ? - Oct 1st 2012, 06:08 PMpnfullerRe: help simplify the expression
- Oct 1st 2012, 06:44 PMProve ItRe: help simplify the expression