Let equation of AB:x+3y=4 Let equation of BC:3x+y=4 Let equation of CA:x+y=0 Now, By solving these equations we get A=(−2,2),B=(1,1) and C=(2,−2) Now, AB=√9+1=√10 BC=√1+9=√10 and CA=√16+16=√32 Since, length of AB and BC are same therefore triangle is isosceles.