Производная от f(x)=4sinx/8cosx/8

Решите задачу:

$\frac{d}{dx}[ \frac{4sin(x)}{8cos(x)}/8]$
$\frac{d}{dx} [ \frac{sin(x)}{2cos(x)}/8]$
$\frac{d}{dx}[ \frac{ \frac{sin(x)}{2cos(x)} }{8} ]$
$\frac{d}{dx} [ \frac{sin(x)}{2cos(x)} * \frac{1}{8} ]$
$\frac{d}{dx} [ \frac{sin(x)}{16cos(x)} ]$
$\frac{1}{16} \frac{d}{dx} [ \frac{sin(x)}{cos(x)} ]$
$\frac{1}{16} \frac{d}{dx}[tan(x)]$
$\frac{1}{16} sec^2(x)$
$\frac{1}{16} \frac{sec^2(x)}{1}$
$\frac{sec^2(x)}{16}$