Because BD bisects AC, we assure that the angle ABD==CBD
Now, if ABD==CBD and we know ADB=90° and CDB=90°, we can assure the remain angles must be equal: ACB==CAB
Therefore, the triangles ABD and CDB are similar. they have the same angles, they share one side, and another side is equal (AD==DC)
the triangles ABD and CDB are similar because they have all their angles equal and at least two of their sides measure the same distance
[tex]\measuredangle ABD=\measuredangle DBC[/tex]
