Answer:
α = 62°
β = 56°
gamma = 90°
Step-by-step explanation:
ΔAOB is isosceles, so m∠A = m∠ABO = 28
28 + 28 + m∠AOB = 180
m∠AOB = 180 - 28 - 28 = 124
β = 180 - 124 = 56
arcAB = 124
ΔBOC is isosceles. α = m∠BCO = 1/2(arc AB) = 1/2(124) = 62
∠D is inscribed in a semicircle
m∠D = gamma = 90°
