Answer:
∠D = 63°
Step-by-step explanation:
Because all four corners of the quadrilateral rest on the circumference of the circle, then BIRD is a cyclic quadrilateral (circle theorem).
According to circle theorem, opposite angles of a cyclic quadrilateral are supplementary (sum to 180°).
∴ ∠I + ∠D = 180°
⇒ ∠D = 180° - ∠I
⇒ ∠D = 180° - 117° (since ∡I = 117°)
∴ ∠D = 63°
