Use the diagram and the given information to find the unknown length.

Answer:
BC is 10 units.
Step-by-step explanation:
Given that, [tex]\frac{AB}{BC}=\frac{AE}{ED}[/tex]
AB=12 units
AD=33 units
AE=18 units
From the figure, AD=AE+ED ⇒ 33=18+ED ⇒ ED=15 units
[tex]\frac{AB}{BC}=\frac{AE}{ED}[/tex]
⇒ [tex]\frac{12}{BC}=\frac{18}{15}[/tex]
⇒ [tex]BC=\frac{12\times 15}{18}=10 units[/tex]
Hence, BC is 10 units.