Question 672315
1st solution
slope AB=(0-4)/(6+2)=-4/8=-1/2
slope BC=0-0/-4-6=0
slope CA=4-0/-2+4=4/2=2
for ABC to be a right triangle slope any two sides should be -1
slope AB*slope CA=-1
so ABC is a right triangle with <A=90deg

2nd solution
|AB|^2=(-2-6)^2+(4-0)^2=80
|BC|^2=(6+4)^2+(0)=100
|CA|^2=(-2+4)^2+(4-0)^2=20
|BC|^2=|AB|^2+|CA|^2
so ABC is a right triangle with <A=90deg
ans