Angle C is inscribed in circle O.
AB is a diameter of circle O.
What is the measure of ZB?

Answer:
∠ B = 19°
Step-by-step explanation:
note ∠ C = 90° ( angle in a semi- circle )
The sum of the 3 angles in the triangle = 180°, thus
∠ B = 180° - (90 + 71)° = 180° - 161° = 19°