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某日在讲解判定直角三角形全等的一种特殊方法“HL”时,由于学生还未学习勾股定理,所以预设通过动手操作活动来得到结论,即:画一个Rt△ABC,使∠C=90°,直角边AC的长为2 cm,斜边AB的长为3 cm,然后发现所有同学画出的三角形都是全等的,于是得到直角三角形全等的另一种判定方法——“HL”.当我讲到这里时,发现x同学高高地举起了手,说还有一种方法可以直接说明这种判定方法:如图1,在Rt△ABC和
One day when explaining the special method “HL” of the right-angled triangle, because the student has not yet studied the Pythagorean theorem, it is pre-set to reach a conclusion through hands-on activity, namely: draw a Rt △ ABC, so that ∠C=90°, the length of the right-angled side AC is 2 cm, and the length of the oblique side AB is 3 cm. Then all the triangles drawn by the classmates are found to be congruent, so another method of determining the right-angled triangle is obtained. ——“HL”. When I talked here, I found that classmate X raised his hand high and said there is another way to directly explain this method of determination: Figure 1, at Rt △ ABC and