Answer:
∠ BAC = 80°
Step-by-step explanation:
The sum of the interior angles of quadrilateral ACDB = 360°
DB and DC are tangents to the circle, thus
∠ DBA = ∠ ACD = 90° ( angle between tangent/ circle at point of contact )
Thus
∠ BAC + 90° + 90° + 100° = 360°
∠ BAC + 280° = 360° ( subtract 280° from both sides )
∠ BAC = 80°
