已知△ABC中,AB=AC=7.24,BC=10.56求:(1)∠A,∠B (2)S△ABC

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已知△ABC中,AB=AC=7.24,BC=10.56求:(1)∠A,∠B (2)S△ABC
已知△ABC中,AB=AC=7.24,BC=10.56求:(1)∠A,∠B (2)S△ABC

已知△ABC中,AB=AC=7.24,BC=10.56求:(1)∠A,∠B (2)S△ABC
过A做BC的垂线交BC于点D
AB=AC=7.24,BC=10.56
BD=DC=BC/2=5.28
cosB=BD/AB=5.28/7.24=0.729
∠B=43.2°
∠A=180°-2∠B=93.6°
AD=ABsinB=7.24sin43.2°=4.96
S△ABC=AD*BC/2=26.2