Marinada '23

[lang=hr] Dan je pravilni tetraedar $ABCD$. Točke $P$ i $Q$ su redom polovišta dužina $BD$ i $CD$. Koliki kut određuju pravci $AP$ i $BQ$? \\\\ \textit{Napomena:} Kut kojeg određuju pravci $a$ i $b$ jednak je manjem kutu kojeg određuju $a$ i bilo koja translacija pravca $b$. [/lang] [lang=en] A regular tetrahedron $ABCD$ is given. The points $P$ and $Q$ are the midpoints of the lengths $BD$ and $CD$, respectively. What is the size of the angle determined by the lines $AP$ and $BQ$? \\\\ \textit{Note:} The angle determined by lines $a$ and $b$ equals to smaller angle determined by $a$ and any translation of $b$. [/lang]