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题1 在某平静的湖面上空有一监测空气质量状况的气球(处于静止状态),一个置于距湖面20m高处的仪器测得气球的仰角为30°,测得气球在水中的虚像的俯角为60°,则气球距湖面的高度为多少米? 解根据平面镜成像特点及三角
Question 1 In a calm lake, there is a balloon (at rest) monitoring the air quality. An instrument placed 20m above the lake measures the elevation angle of the balloon at 30°. The depression angle of the virtual image of the balloon in the water is measured as At 60°, how many meters is the height of the balloon from the lake?