So here we go, lines OA and OB are radii of the circle O
since the measurement of ∡ O is given it is easy to find the other measurements.
180-85 = 95° (all the sides of a triangle = 180°)
That angle divided by two
\(\frac{95}{2}\) = 47.5°
We know that the radii are the sides which makes that triangle isosceles.
So m∡BAC = 47.5°
Answer is B)47.5
