Answer:
Angle-Angle-Side (AAS)
Step-by-step explanation:
Given triangles; ΔABD and ΔCBD
<A = <C = (right angle property)
AB ║ DC (given)
Then,
DA ║ CB
<B ≅ <D (congruent property)
DB ≅ BD (similarity property)
<D + <B = <B + <D (complementary angles, and property of triangles)
Therefore by Angle-Angle-Side (AAS),
∆ABD ≅ ∆CBD