Quadrilaterals formed by joining the mid- points of the sides of a quadrilateral PQRS taken in order, is a rectangle, if____.
Diagonal of PQRS are perpendicular
Since the quadrilateral, ABCD formed by joining the mid – points of quadrilaterals PQRS is a rectangle,
AC = BD [Diagonals of rectangle are equal]
PQ = QR
Thus, quadrilateral PQRS is a rhombus.
Hence, diagonal of PQRS i.e., PR and QS are perpendicular. [Since diagonals of rhombus are perpendicular to each other]