题目

如图，小明在楼上点A处观察旗杆BC，测得旗杆顶部B的仰角为30°，测得旗杆底部C的俯角为60°，已知点A距地面的高AD为12m．求旗杆的高度．                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       答案：答案：解：过点A作AE⊥BC，垂足为E，得矩形ADCE，∴CE=AD=12.      PC=PA·cos∠APC=30…………………………………2分      在Rt△PCB中，………………………1分    …………………………………2分 答：当渔船位于P南偏东45°方向时，渔船与P的距离是30海里。……1分

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