Question 192611
check  slope  os  AB  and  BC

m(AB) = ( y2-y1)/(x2-x1)=(-2--4)/(-9--4)=(2)/(-5) =(-2/5)

m(BC) = (-4--9)/(-4--6) = (5/2)

as  slopes  are  negative  reciprocals,  m(AB)=-1/m(BC),  they  are  perpendicular

as  such  angle  ABC  is  90  degrees  and  triangle  is  a  right  triangle  by  definition