A similar triangle means it is of a diferent size, but the sides or angles are proportionaly the same.
Use the rule of 3 on each number, to find the equivalent sides:
65 - 39
60 - x
(60 * 39) / 65
2340 / 65
36cm
60 - 36
25 - x
(25*36) / 60
900 / 60
15cm
Original triangle: 65, 60, 25
Similar triangle: 39, 36, 15
Answer:
![\boxed{\bf~The~smallest~side~of~the~trianlge~measures~15cm.}](https://img.qammunity.org/2019/formulas/mathematics/high-school/wm4a5zkcw5y1ocfa033y9ibhd7obhmf2n1.png)
Hope it helped,
Happy homework/ study/ exam!