In this case, we have to use the SSS Postulate for the congruency of the triangles, that is, if three sides of a triangle are congruent to three sides of another triangle, then the triangles are congruent.
We have that all reasons are given congruent sides. The midpoint divides the segment into two equal parts, then the angles are congruent because of the reason: SSS ( SSS Postulate for congruency of triangles).