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在初三数学第一轮复习时,曾经出现这样一道选择题:“下列轴对称图形中,只用一把无刻度的直尺不能画出对称轴的是().A.菱形B.矩形C.等腰梯形D.正五边形”.当时我们数学备课组同行们普遍选B,以后也没有人提出异议.(包括学生)无独有偶,2013年我区初二期末考试选择题中的压轴题就是这样一道试题.当时阅卷教师也大多选B,认为矩形无法用无刻度的直尺画出对称轴,评分标准也支持选项B,似乎顺利顺章!但有一位教师提出了质疑,引发了教师间的大讨论,曾一度停止阅卷,……矩形用无刻度的直尺真的无法画出它的对称轴吗?
In the first three math first round of review, there have been such a multiple-choice questions: “The following axisymmetric graphics, only a non-scale ruler can not draw the axis of symmetry is (A.) Diamond B. Rectangle C. Isosceles trapezoid D. Regular pentagons ”At that time, our mathematics lesson preparation group counterparts generally selected B, no one objected later. (Including students) Coincidentally, Finale problem is such a test questions. At that time, most of the marking teachers also choose B, that the rectangle can not be drawn with a straight scale without scale axis of symmetry, the score also supports option B, seems smooth Shun Zhang! But one teacher questioned, trigger The discussion between teachers, once stopped marking, ... Rectangle with no scale ruler really can not draw its axis of symmetry it?