△ABC and △DBC are two isosceles triangles on the same base BC (see the given figure). Then, ∠ABD = _______.

△ABC and △DBC are two isosceles triangles on the same base BC (see

1.	△ABC and △DBC are two isosceles triangles on the same base BC (see the given figure). Then, ∠ABD = _______.
Answer» $△ A B C$ and $△ D B C$ are two isosceles triangles on the same base BC (see the given figure). Then, $∠ A B D$ = _______.