Question

show that points P(1,-2) ,Q(5,2) ,R(3,-1) , (-1,-5) are the vertices of a parallelogram?​

Answer 1

Since, Diagonals are un -equal and opposite sides are equal .

=> PQRS is a parallelogram . 

here are your answers in two images ..

Answer 2

PQRS is a parallelogram if and only if the mid point of the diagonals PR is same as that of the mid-point of QS.

PQRS is a parallelogram if and only if the mid point of the diagonals PR is same as that of the mid-point of QS. That is, if and only if