9514 1404 393
Answer:
32.7°
Explanation:
Solve the given equation for C, then fill in the given values and evaluate.
C = arccos((a² +b² -c²)/(2ab))
Y = arccos((50² +90² -55²)/(2·50·90)) = arccos(7575/9000) ≈ 32.7°
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Y is angle A in the attached triangle solver.