Question

please tell me this solution​

Answer 1

Step-by-step explanation:

Given -- ABC is an isosceles triangle, AB=AD and BD=CD.

To prove -- AD bisects ∠A and ∠D.

Proof -- Let O be the point from where AD cut BC.

In triangle ABO and ACO

                 AB=AC                    (given)

            ∠ABC=∠ACB                (angle opposite to equal sides are equal)

                AD=AD                     (common)

∴ by SAS criteria ΔABO≅ΔACO

so, ∠BAO=∠CAO   (by C.P.C.T)

hence, ∠A is bisected by AD.                                proved

now, In triangle DBO and DCO

               DB=DC                       (given)

          ∠DBO=∠DCO                  (angle opposite to equal sides are equal)

               DO=DO                      (common)

∴ by SAS criteria ΔDBO≅ΔDCO

so, ∠DBO=∠DCO    (by C.P.C.T)

hence, ∠D is bisected by AD.                                proved.