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小明的爸爸是一位数学老师.一天,爸爸把小明叫到厨房,拿了一棵圆柱形的大葱对小明说:“这里有两个数学问题,你来思考一下.”小明的心中充满疑惑,爸爸用刀把大葱斜切成两段,拿起一段(图1)问小明:“这个截面的轮廓是什么曲线?”小明马上回答:“太简单了,是椭圆,我们数学课本里有证明过程.”爸爸接着用刀轻轻地沿葱轴中心线方向把最外层葱皮划开(图2)、剥下,在菜板上把圆柱状的葱皮展开铺平(图3),“刚才的椭圆展平后变成了什么曲线?这个问题课本里没有,你自己研究一下.”
Xiao Ming’s father is a math teacher.One day, my father called Xiao Ming to the kitchen, took a cylindrical green onion on Xiao Ming said: “There are two math problems, you think about it.” Xiao Ming’s heart full Doubt, my father cut the scallion with a knife in two, pick up a section (Figure 1) asked Xiao Ming: “What is the outline of the cross section?” “Xiao Ming immediately replied: ” too simple is elliptical, our math textbook There is a proof process. “” Father then gently knife along the axis of the center line of the onion to the outermost open onions skin (Figure 2), peeled off, on the cutting board to open cylindrical onion scallops Figure 3), “What curve has just become after the flattening of the ellipse? There is no text in this question, and you study it yourself.” "