SSS congruence
Given triangle ABC with three sides a,b,and c
Construct triangle DEF such that DE=AB ,DF=AC,EF=BC
use sliders to resize DE and EF and drag point F to resize DF
when corresponding sides of both the triangles are equal then drag point D and make it lie over triangle ABC.
You can move vertices A,B and C to form different triangles

Do the triangles overlap each other completely.
If yes then By SSS(side-side-side) congruence the two triangles are congruent .