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阳光灿烂的早晨,操场上的一只篮球的影子边缘是椭圆.同学们是否想过,影子为什么是椭圆?这个椭圆的焦点、准线在哪里?长轴、短轴长与球的半径有什么关系?如果不是白天而是漆黑的夜晚,一盏孤灯下的球的影子又是什么图形?
On a sunny morning, the edge of the shadow of a basketball on the playground is an ellipse. Have students thought about why the shadow is an ellipse? Where is the focus and alignment of this ellipse? What is the long axis, short axis length, and radius of the ball? Relationship? If it is not the dark day but the night, what is the shadow of a ball under a solitary lamp?