[tex]Zadanie\\\\AB=a=12\ cm\\P_{ABC} =90\ cm^{2}\\P_{CDE}=120\ cm^{2}\\CD=h_{1}\\EF= h_{2}\\\\ P_{ABC} =\frac{1}{2}\cdot a\cdot h_{1}\\\\\frac{1}{2} \cdot 12\cdot h_{1}=90\\\\6\cdot h_{1}=90\ \ \mid:6 \\\\h_{1}=15\ cm \\\\ P_{CDE}= \frac{1}{2}\cdot h_{1} \cdot h_{2}\\\\ \frac{1}{2} \cdot 15\cdot h_{2}= 120\\\\ 7,5\cdot h_{2}=120\ \ \mid:7,5\\\\ h_{2}=16\ cm\\\\Odp.\ Odcinek \mid EF\mid =h_{2} \ ma\ 16\ cm\ dlugosci[/tex]
