Explanation
Similar triangles are triangles that have the same shape, but their sizes may vary
From the given question, we have that
[tex]\triangle ABC\text{ is similar to }\triangle DEF[/tex]
Then, we can take the ratio of the sides:
[tex]\frac{BC}{AC}=\frac{EF}{DF}[/tex][tex]\begin{gathered} Where \\ BC=4cm \\ AC=6cm \\ EF=? \\ DF=18cm \end{gathered}[/tex]
So that
[tex]\begin{gathered} \frac{4}{6}=\frac{EF}{18} \\ \\ EF=\frac{18\times4}{6} \\ \\ EF=12 \end{gathered}[/tex]
The value of the side EF is 12cm
