opgave d

$
\sin ^2 (x) = \frac{1}{2}
$
$
\sin (x) =  - \sqrt {\frac{1}{2}}
$ of $
\sin (x) = \sqrt {\frac{1}{2}}
$
$
\sin (x) =  - \frac{1}{2}\sqrt 2
$ of $
\sin (x) = \frac{1}{2}\sqrt 2
$
$
x = 1\frac{1}{4}\pi  + k \cdot 2\pi
$ of $
x = 1\frac{3}{4}\pi  + k \cdot 2\pi
$ of $
x = \frac{1}{4}\pi  + k \cdot 2\pi
$ of $
x = \frac{3}{4}\pi  + k \cdot 2\pi
$
$
x = \frac{1}{4}\pi  + k \cdot \frac{1}{2}\pi
$