Question

explain why segments connecting any pair of corresponding verticals of congruent pentagons are congruent.

Answer 1

A "convex hull" is the set of points forming the smallest convex set that includes all of the points. Thus, the convex hull of two polygons is the smallest single convex polygon that encloses the two polygons.
Learn more about it at:
http://mathworld.wolfram.com/ConvexHull.html

Answer 2

ok thanks