Answer
a) No
b) Yes
Work Step by Step
a) If the corresponding sides are congruent, there is nothing that restricts all of the angles of the trapezoid from changing. Thus, it is impossible to say that the trapezoids are congruent.
b) Unlike case A, now the length of the third side is set. Once this length is set, the angles will no longer be able to change, so the trapezoids will be congruent.
