Answer :
let the three points A(0,0), B(a,0), C(b.0)form a triangle
if it is a right angled triangle at A then by Pythagoras theorem
[tex] AB^{2} + AC^{2} = BC^{2} [/tex]
[tex] a^{2} + b^{2} = \sqrt{ a^{2}+ b^{2} } ^{2} [/tex]
[tex] a^{2} + b^{2}=a^{2} + b^{2} [/tex]
hence proved
if it is a right angled triangle at A then by Pythagoras theorem
[tex] AB^{2} + AC^{2} = BC^{2} [/tex]
[tex] a^{2} + b^{2} = \sqrt{ a^{2}+ b^{2} } ^{2} [/tex]
[tex] a^{2} + b^{2}=a^{2} + b^{2} [/tex]
hence proved