1) slope -4/5 and slope 4/5 are not negative reciprocls.

If they were, then the figure would have been a square.

As it is, the figure is a parallelogram, or more specifically, a rhombus.

2) Solve for the slopes of the 3 sides.

If there are two slopes that are negative reciprocals, then PQR is a right

triangle.

If two lines are perpendicular, then their slopes are negative reciprocals.