$$2 \cos{\left(x \right)} \sinh{\left(x \right)}$$
2*(cos(x)*cosh(x) - sin(x)*sinh(x))
$$2 \left(- \sin{\left(x \right)} \sinh{\left(x \right)} + \cos{\left(x \right)} \cosh{\left(x \right)}\right)$$
$$- 4 \sin{\left(x \right)} \cosh{\left(x \right)}$$