When two triangles are similar, the ratio between their corresponding sides is equal to a constant(the scale factor between the triangles). The original triangles in our problem have a scale factor of 3:
![(3a)/(a)=(3b)/(b)=(3c)/(c)=3](https://img.qammunity.org/2023/formulas/mathematics/college/ukoepabmqm801zmkc6d1u2wccx1cis4mqu.png)
If we add 6 to the sides of both triangles, this is no longer true. We can't rewrite the ratio between the corresponding sides as a constant:
![(3a+6)/(a+6)\\e k](https://img.qammunity.org/2023/formulas/mathematics/college/449oh6vj0ujbtuim5uh45gv9xb251esl9r.png)
therefore, the triangles wouldn't be similar.