论文部分内容阅读
一位老师运用启发式教学,精心设计了“三角形内角和”这堂课,学生思维十分活跃.当师生共同得出“三角形内角和等于180°”这一结论后,一个女同学兴奋地向大家介绍说,她发现了另一个规律——“三角形外角和等于900°!”这位老师当即表扬了她,说她肯动脑筋,有独创精神,并肯定了这一规律的正确性.众所周知,我们是这样定义三角形外角的:三角形的角的一边与另一边的反向延长线所组成的角,叫做三角形的外角.如图1中的∠1、∠2、∠3、∠4、∠5、∠6,都是△ABC的外角.就是说,
A teacher using heuristic teaching, carefully designed “triangle angle and ” This class, the students thinking is very active.When teachers and students come together “triangle internal angle and equal to 180 ” this conclusion, a woman Students excited to tell you that she found another law - “triangle outer corner and equal to 900 °!” The teacher immediately praised her, said she was willing to use their brains, creative, and affirmed this As we all know, we are the definition of the outer corner of the triangle: one side of the triangle and the other side of the reverse extension of the angle formed by the angle, called the outer corner of the triangle.As shown in Figure 1 ∠1, ∠2, ∠ 3, ∠4, ∠5, ∠6, are the outer corners of △ ABC. That is,