If we calculate the similarity ratio of these triangles:
*Similarity ratio, also called scale factor is the ratio between their sides
[tex]\begin{gathered} SF=\frac{length\text{triangle ZYG}}{\text{length triangle BRP}} \\ SF=\frac{42}{21}=2 \\ SF=\frac{96}{48}=2 \\ SF=\frac{56}{28}=2 \end{gathered}[/tex]
The triangles have a similarity ratio of 2, that means its sides are congruent then they would be similar by the theorem SSS (Side-Side-Side)
