Răspuns:
[tex]\boldsymbol {\red{51}}[/tex]
Explicație pas cu pas:
CD||AB ⇒ ΔECD ~ ΔEBA
[tex]\dfrac{EC}{EB} = \dfrac{ED}{EA} = \dfrac{CD}{AB} \Rightarrow \dfrac{EB - EC}{EB} = \dfrac{EA - ED}{EA} = \dfrac{AB - CD}{AB} \\ [/tex]
[tex]\dfrac{BC}{EB} = \dfrac{AD}{ED} = \dfrac{15 - 10}{15} \Rightarrow \dfrac{6}{EB} = \dfrac{6}{ED} = \dfrac{5}{15} \\ [/tex]
[tex]\dfrac{6}{EB} = \dfrac{5}{15} \Rightarrow EB = \dfrac{6 \cdot 15}{5} = 18 \ cm \\ [/tex]
[tex]\dfrac{6}{ED} = \dfrac{5}{15} \Rightarrow ED = \dfrac{6 \cdot 15}{5} = 18 \ cm \\ [/tex]
Perimetrul triunghiului EBA:
[tex]P = EB++ED+AB = 2\cdot18 + 15 = 36+15 = \bf 51 \ cm[/tex]