It is clear that △ABC is a right angled triangle at A . ∴ Circum-centre, S= Mid-point of hypotenuse BC =(2−1+1,21−1)=(0,0)
Orthocentre, O= Coordinate of vertices at which right angle is there =A=(1,1)
and Incentre I=(22+2+222×1+2×1+2×(−1)22+2+222×1+2×1+2×−1<br/>) =(22+422,22+422)=(2−1,2−1) IS+OS=(2−1)2+(2−1)2+(1)2+(1)2 =2(2−1)+2=2−2+2=2