Respuesta :

Answer:

60°

Step-by-step explanation:

sum of interior angles of quadrilateral is 360°

∠C = 70°

∠D = 50°

∠C + ∠D = 120°

∴ ∠A + ∠B = 360° - 120° =240°

AO and BO bisect ∠A and ∠B

∠OAB + ∠OBA = 1/2 x ( ∠A + ∠B) = 120°

∠AOB = 180° - (∠OAB + ∠OBA) = 180° - 120° = 60°

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