Solution: solution: ∵AD is the high line of BC side.
If BC is the bottom, that is, AB=AC, as shown in figure (1),
∴BD=DC,AD⊥BC,∠BAD=∠CAD
AD = BD
∴∠B=∠BAD=45
∴∠BAC=2∠BAD=90
If BC is waist BC=BA,
(1) If point D is on the side of BC, as shown in Figure (2),
And then in rt delta bad,
BA = 2AD,
∴∠B=30,
∴∠bac=75;
② If point D is on the extension line of CB, as shown in Figure (3),
Similarly, DBA = 30,
Then: ∠ ABC = 150,
∴∠BAC= 15。