Xét \(\Delta ABC \ và \ \Delta C'B'A'\)có:
\(\dfrac{AB}{C'A'}=\dfrac{12}{8}=\dfrac{3}{2}\\ \dfrac{BC}{A'B'}=\dfrac{18}{12}=\dfrac{3}{2}\\ \dfrac{CA}{B'C'}=\dfrac{27}{18}=\dfrac{3}{2}\\ =>\dfrac{AB}{C'A'}=\dfrac{BC}{A'B'}=\dfrac{CA}{B'C'}\)
=>\(\Delta ABC\) đồng dạng vs \(\Delta C'B'A'\)