# Math Help - Trigonometry question

1. ## Trigonometry question

Hi,
I need help to derivate the following equation :

Arc tan (square(x-1)/x)

I can't get the correct answer which is : (2-x)/2(x^2+x-1) square (x-1)

Here is what I've done so far :

du/a^2+u^2

so :

du = 1/2square(x-1)
a^2 = x^2
u^2 = (x-1)
which give me :
1/2(x^2+x-1) square (x-1)

can't find where the 2 - x come from

thx for the help

2. ## Re: Trigonometry question

Hey Garet.

Have you tried using a right angled triangle to get the simplification? (That is, one with a right angle and hypotenuse with the sine/cos/tan relationships?)

3. ## Re: Trigonometry question

Could you rewrite the question. The logic for the question is simple using function of a function rule.