To find if the corresponding sides are proportional you use the next:
[tex]\begin{gathered} \frac{AB}{A^{\prime}B^{\prime}}=\frac{BC}{B^{\prime}C^{\prime}}=\frac{CA}{C^{\prime}A} \\ \\ \end{gathered}[/tex]
Then, for the given traingles:
[tex]\begin{gathered} \frac{7}{12.6}=0.55 \\ \\ \frac{24}{43.2}=0.55 \\ \\ \frac{25}{45}=0.55 \end{gathered}[/tex]As the ration between the corresponding sides is the same (0.55) they are proportional.The triangles are similars as the corresponding sides are proportional.
