问题
填空题
在△ABC中，A+C=2B，BC=5，且△ABC的面积为10
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答案
∵A+C=2B
∴A+C+B=2B+B=π
∴B=π 3
根据面积公式S△ABC=
AB?BC?sinB=1 2
?AB?5?sin2
=10π 3 3
∴AB=8
故答案为：
，8．π 3
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在△ABC中，A+C=2B，BC=5，且△ABC的面积为10
|
∵A+C=2B
∴A+C+B=2B+B=π
∴B=π 3
根据面积公式S△ABC=
AB?BC?sinB=1 2
?AB?5?sin2
=10π 3 3
∴AB=8
故答案为：
，8．π 3
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| While I was waiting to enter university, I saw in a newspaper a teaching job wanted at a school about ten miles from where I___1___. Being very short of money and wanting to___2___ something useful I applied (申请). Fearing as I did so, that without a degree and with no ___3___ of teaching my chances of getting the job were ___4___ However, three days later, a letter ___5___, calling me to Croydon for a___6___with the headmaster. It proved to be a___7___journey: a train to Croydon station, a ten-minute bus ride and then a walk of at ___8___ a quarter of a mile. As a result I arrived there, feeling___9___hot to be nervous. It was clearly the ___10___ himself that opened the door. He was___11___and round. “The school,” he said, “is made up of one___12___of twenty-four boys between seven and thirteen.” I should have to___13___all the subjects except art, which he taught himself. I should have to___14___the class into three groups and teach them in turn at three different___15___, and I was disappointed at the thought of teaching maths-a___16___at which I wasn’t very good at school. Worse perhaps was the idea of___17___to teach them on Saturday afternoon because most of my friends would be___18___ themselves at that time. Before I had time to ask about my salary (薪水), he got up to his___19___. “Now,” he said, “you’d better meet my wife. She is the one who really 20 this school.” | ||||
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