So ∠ AED = 90, ∠ AFD = 90 (vertical meaning).
∠AED=∠AFD (equivalent substitution)
Because AD is the angular bisector of △ABC (known)
So ∠DAE=∠DAF (definition of angular bisector)
In δ δ△ADE and δ△ADF,
{_∠DAE=∠DAF_,
{∠AED=∠AFD,
{_ ad = ad _ (male * * *)
So △ADE is equal to△ △ADF (A.A.S).