in PQRS
PR = QS
P and S are right angles
how to prove PQRS is a parallelogram?
i had proved triangle QPS is congruent to triangle RSP
what should i do next to prove PQRS is a parallelogram?
Clearly the line segments PQ & SR are parallel being perpendicular to the same line.
From congruent triangles you see that PQ & SR have the same length.
Is that enough?