Answer:

∠OAB = 25°

Step-by-step explanation:

Construction: Join BO

∠APB = 50° (Given)

∠PAO = 90° (Angle between tangent and radius)

∠PAB = ∠PBA

∠APB + ∠PBA + ∠PAB = 180° (Angle sum property)

50° + 2∠PAB = 180°

2∠PAB = 180° - 50°

2∠PAB = 130°

∠PAB = 130°/2

∠PAB = 65°

∠OAB = ∠PAO - ∠PAB

= 90° - 50°

= 25°

Therefore, ∠OAB = 25°