geometry
posted by jasmine .
7. Verify that parallelogram ABCD with vertices A(–5, –1), B(–9, 6), C(–1, 5), and D(3, –2) is a rhombus by showing that it is a parallelogram with perpendicular diagonals.

easy,
after making sketch, show that the slopes of opposite sides are equal.
Then draw the diagonals and find their slopes
show that the slope of one diagonal is the opposite reciprocal of the slope of the other.
Be careful in your slope calculations with the subtraction of all those negative numbers
I will do one slope
slope AB = (6(1))/(9  (5)) = 7/4 or 7/4 
do ur own homework

what she needs is the formula...(that is helping not doing the work)

(y2y1)/(x2x1)
that is the formula