triangle ABC
D is the midpoint of BC
DE perpendicular to AB
And DF perpendicular to AC
DE=DF
To prove:
Triangle ABC is an isosceles triangle
Proof:
In the right angles triangle BED and CDF
Hypotenuse BD=DC ( because D is a midpoint )
Side DF=DE ( given)
△BED≅CDF ( RHS axiom)
∠C=∠B
AB=AC ( sides opposite to equal angles
△ABC is an isosceles triangle