Triangle ABC is congruent to triangle DEF.

Which statement must be true about the triangle

In triangle abc segment de is parallel to the side ac . (the endpoints of segment de lie on the sides ab and bc respectively). find de, if ac=20cm, ab=17cm, and bd=11.9cm;

What is the relationship between all triangles that can be drawn given the same three angles

In the diagram below? p is circumscribed about quadrilateral abcd. what is the value of x