Answer:

ABD angle is congruent to angle ACD by congruency of the two triangles and sorry other questions I can't understand

Answer:

In triangle

∆ADB and ∆ADC

AB=AC. (given)

angles ABD=ACD. (angle opposite to equal side)

angles ADB=ADC. ( each 90°)

therefore, ∆ADB ≈ ∆ADC. ( by AAS)........1

c). from equation 1 BD=CD. ( by C.P.C.T)

that is D is mid point of BC