Answer:
∠B=19°
Step-by-step explanation:
At the endpoints of a diameter, angle c meets the circle. It intercepts a 180-degree arc.We know that the measure of C is 90 degrees because the measure of an inscribed angle is half the measure of its intercepted arc. Angles of triangle of ABC must add up to 180.
m∠A+m∠B+m∠C= 180°
71°+m∠B+90°=180°
m∠B+161°=180°
m∠B=19°
