According to the question,
We have,
ACB and ADB are two right triangles.
To Prove: ∠BAC = ∠BDC
We know that,
ACB and ADB are right angled triangles,
Then,
∠C + ∠D = 90° + 90°
∠C + ∠D = 180°
Therefore ADBC is a cyclic quadrilateral as sum of opposite angles of a cyclic quadrilateral = 180°
We also have,
∠BAC and ∠BDC lie in the same segment BC and angles in the same segment of a circle are equal.
∴ ∠BAC = ∠BDC.
Hence Proved.