Pochodna funkcji cos(t/a)

$f\left(a, t\right) =$	$\cos\left(\dfrac{t}{a}\right)$
$\dfrac{\mathrm{d}\left(f\left(a, t\right)\right)}{\mathrm{d}x} =$	$\class{steps-node}{\cssId{steps-node-1}{\tfrac{\mathrm{d}}{\mathrm{d}x}\kern-.25em\left(\cos\left(\dfrac{t}{a}\right)\right)}}$ $=\class{steps-node}{\cssId{steps-node-2}{0}}$

$f\left(a, t\right) =$

$\cos\left(\dfrac{t}{a}\right)$

$\dfrac{\mathrm{d}\left(f\left(a, t\right)\right)}{\mathrm{d}x} =$

$\class{steps-node}{\cssId{steps-node-1}{\tfrac{\mathrm{d}}{\mathrm{d}x}\kern-.25em\left(\cos\left(\dfrac{t}{a}\right)\right)}}$

$=\class{steps-node}{\cssId{steps-node-2}{0}}$