Question

Ex 5!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 1

$\it \mathcal{A}_{ABC}=\dfrac{AC\cdot BE}{2} \Rightarrow \dfrac{\mathcal{A}_{ABCD}}{2}=\dfrac{15\cdot6}{2} \Rightarrow \mathcal{A}_{ABCD}=90\ cm^2\ \ \ \ \ \ (1)\\ \\ \\ \mathcal{A}_{ABCD}=AB\cdot DF \Rightarrow \mathcal{A}_{ABCD}=10\cdot DF\ \ \ \ \ (2)\\ \\ (1),\ (2) \Rightarrow 10\cdot DF=90 \Rightarrow DF=9\ cm$

Răspunsul  corect  este  b) 9cm