opgave c

$
\sin (x)\cos (x) - \sin (x) = 0
$
$
\sin (x)\left( {\cos (x) - 1} \right) = 0
$
$
\sin (x) = 0
$ of $
\cos (x) - 1 = 0
$
$
x = k \cdot \pi
$ of $
\cos (x) = 1
$
$
x = k \cdot \pi
$ of $
x = \frac{1}{2}\pi  + k \cdot \pi
$
$
x = k \cdot \frac{1}{2}\pi
$