# How do you find the derivative of the function y=cos((1-e^(2x))/(1+e^(2x)))?

$y ' = 4 \cdot {e}^{2 \cdot x} / {\left(1 + {e}^{2 + x}\right)}^{2} \cdot \sin \left(\frac{1 - {e}^{2 x}}{1 + {e}^{2 \cdot x}}\right)$
$y ' = - \sin \left(\frac{1 - {e}^{2 x}}{1 + {e}^{2 x}}\right) \cdot \frac{- 2 {e}^{2 x} \left(1 + {e}^{2 x}\right) - \left(1 - {e}^{2 x}\right) \cdot {e}^{2 x}}{1 + {e}^{2 x}} ^ 2$
$y = - \sin \left(\frac{1 - {e}^{2 x}}{1 + {e}^{2 x}}\right) \cdot \left(2 {e}^{2 x} \frac{- 1 - {e}^{2 x} - 1 + {e}^{2 x}}{1 + {e}^{2 x}} ^ 2\right)$
$y ' = 4 {e}^{2 x} / {\left(1 + {e}^{2 x}\right)}^{2} \cdot \sin \left(\frac{1 - {e}^{2 x}}{1 + {e}^{2 x}}\right)$