Answer:
BC = 23.8
Step-by-step explanation:
See the diagram attached.
Given AC ║ DE and BD = 5, DA = 12 and BE = 7.
We have to find BC.
Since, AC ║ DE, so, Δ ABC and Δ DBE are similar.
If two triangles are similar then the ratio of their corresponding sides remains the same.
Hence, [tex]\frac{BD}{BA} = \frac{BE}{BC}[/tex]
⇒ [tex]\frac{5}{12 + 5} = \frac{7}{BC}[/tex]
⇒ [tex]BC = \frac{7 \times 17}{5} = 23.8[/tex] (Answer)