Triangle ABC have coordinates (1,5)(-3,7) and (-2,-1)

show the triangle is right - angled.

mAB= 5-7/1--3 = - 1/2

mBC= 7--1/-3--2 = -1 1/5

mCA= -1-5/-2-1= 2/1 = 2

-1/2 and 2 are perpendicular gradients meaning it is a right angle

Am i right with this question or COMPLETELY off the mark???