Right triangle PQR is to be constructed in the xy-plane so that the right angle is at P and PR is parallel to the x-axis. The x- and y-coordinates of P, Q, and R are to be integers that satisfy the inequalities -4 < or= x < or = 5 and 6 < or= y < or = 16. How many different triangles with these properties could be constructed?
P can be chosen from 11*10 points and Q can be chosen from 10 points and R from 9 points
Answer = 11*10*10*9 = 9900