In quadrilateral pqrs, the coordinates are p(o, o), q(a+c, o), r(2a+c, b., and s(a, b. how can you use coordinate geometry to show that the diagonals are perpendicular?

Given:
  Quadrilateral PQRS
  P(o, o), Q(a+c, o), R(2a+c, b), S(a, b)
Find:
  whether the diagonals are perpendicular using coordinate geometry
Solution:
  If the diagonals are perpendicular, their slopes multiply to give -1.
The slope of PR is
  (b-o)/(2a+c-o)
The slope of QS is
  (b-o)/(a-(a+c)) = (b-o)/(-c)
The product of these slopes is
  (b-o)·(b-o)/((2a+c-o)(-c))
This value will not be -1 except for very specific values of a, b, c, and o.

It cannot be concluded that the diagonals of PQRS are perpendicular based on the given coordinates.

Is there an attachment available?