If we calculate the similarity ratio of these triangles:
*Similarity ratio, also called scale factor is the ratio between their sides
![\begin{gathered} SF=\frac{length\text{triangle ZYG}}{\text{length triangle BRP}} \\ SF=(42)/(21)=2 \\ SF=(96)/(48)=2 \\ SF=(56)/(28)=2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/gz2kq8vqj8yi5n8w3qw2axh856e7rl96ez.png)
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)