In ΔABC, ∠B = 90° and BD ⊥ AC. Prove that ∠ABD = ∠ACB.
Let ∠ABD = x and ∠ACB = y
According to question,
∠B = 90O
In triangle BDC, we have,
∠BDC = 90O
∠DBC = (90 – x)O
∠BDC + ∠DBC + ∠DCB = 180O
90O + (90 – x)O + y = 180O
180O – x + y = 180O
x = y
So,
∠ABD = ∠ACB