Marinada '21

[lang=hr] U trapezu $ABCD$ s osnovicama $\overline{AB}$ i $\overline{CD}$ je $\angle ADC= \angle ACB$. Odredi duljinu dužine $\overline{AC}$ ako je duljina srednjice trapeza $13$, a duljine osnovica odnose se kao $4~\colon9$. [/lang] [lang=en] In the trapezium $ABCD$, the bases are $\overline{AB}$ and $\overline{CD}$. It is known that $\angle ADC= \angle ACB$, that the length of the midline is $13$, and that the ratio of the lengths of the bases is $4~\colon9$. What is the length of the segment $\overline{AC}$? [/lang]