Answer:
see explanation
Step-by-step explanation:
(a)
OC = OB ( both radii of the circle )
Thus Δ BOC is isosceles with congruent base angles.
∠ BOC = ∠ BCO = 50°
(b)
∠ ACB = 90° ( angle in a semicircle ), then
∠ ACO = 90° - 50° = 40°
OA = OC ( both radii of the circle )
Thus Δ ACO is isosceles with congruent base angles.
∠ BAC = ∠ ACO = 40°
