4. BE and CF are two equal altitudes of a triangle ABC. Using RHS congruence rule, prove that the triangle ABC is isosceles.
Using the given conditions, consider and ,
(i) (Right angle)
(ii) (Common in both the triangles)
(iii) (Given that altitudes are of the same length. )
Thus by RHS axiom, we can say that :
Hence by c.p.c.t.,
And thus (sides opposite to equal angles are also equal). Thus ABC is an isosceles triangle.