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圆柱体的认识小学数学第九册教材中所讲的圆柱,是指的直圆柱(圆柱的母线若垂直于底面,便是直圆柱)。教材没有给圆柱下定义,只是通过实例引出圆柱的概念。只要求学生认识圆柱体及其底面和高。对圆柱的两个底面,教材明确提出了它们的大小关系(上、下底面是相等的两个圆),而没有明确提出它们的位置关系(平行),但它定义圆柱的高为:
The understanding of the cylinder Primary school mathematics textbook ninth column, said cylinder, is the straight cylinder (cylinder of the bus if perpendicular to the bottom, is a straight cylinder). Textbook did not define the cylinder, just through the example of the concept of cylinder. Only ask students to recognize the cylinder and its underside and height. For the two bottom surfaces of the cylinder, the text clearly states their size relationship (the upper and lower bottom surfaces are equal two circles) without explicitly specifying their positional relationship (parallel), but it defines the height of the cylinder as: