HG 25
T37. In a quadrilateral ABCD let B and C be right angles. If the perpendicular
bisector of AD is perpendicular to BC, then ABCD is a SQ.
T38. If a rectangle exists, its opposite sides are equal.
T39. In a SQ, the line joining the midpoints of the legs is bisected perpendicularly
by the line joining the midpoints of the base and summit.