Question 812015
y=mx+b
slopes
4-1
-1-3

m=-3/4 slope
3,1
0,-3
1--3=4
3-0=3
m=4/3 slope
-3/4*4/3=-1 product of the slopes=-1 so they are perpendicular
sides AB and BC are perpendicular and form  a right angle. So, yes it is a right triangle