Question

#5 please and thank you

Answer 1

D is the midpoint of segment BC.(given)
Let's add another given saying angle 1 is congruent to angle 2.
Let's prove that triangle ADB is congruent to triangle ADC
So BD=DC (definition of midpoint) and AD=AD (reflexive prop) and measure of angle 1= measure of angle 2. So using SAS post. we get that triangle ADB= triangle ADC.