2. the coordinates of the vertices of are p(-2,5), q(-1,1) and r(7,3) . determine whether pqr is a right triangle. show your work.

Check the picture below.





now, two lines who meet at a perpendicular angle, have a negative reciprocal slope of each other, to make it short, if you multiply their slopes, you should get -1 as the product, if they're indeed perpendicular.



low and behold, they're indeed perpendicular, thus that angle is indeed a right-angle.