平行四边形的判定(1)是上海教育出版社九年义务教育数学课本八年级22.2(3)节,继平行四边形性质后进入平行四边形判定方法探讨第一节课。学生刚从边、角、对角线及图形对称性等方面进行了平行四边形性质学习。同时,判定方法往往是性质定理逆命题。如平行线性质定理与判定定理、一些特殊三角形判定与性质的互逆等。前面学习线段中垂线性质定理以逆定理、角平分线性质定理及逆定理时也给出了很好的示范,给本节课类比的导入方法奠定了基础。课本在平 Parallelogram (1) is the Shanghai Education Press nine-year compulsory education mathematics textbook grade eight grade 22.2 (3), following the parallelogram into the method of determining the parallelogram of the first class. Students just from the side, angle, diagonal and graphical symmetry and other aspects of the parallelogram nature of learning. At the same time, the judgment method is often the opposite of the nature theorem. Such as the theorem of parallel lines and the theorem of judgment, the reciprocity of some special triangles and nature. The previous study of the vertical line theorem in the line segment also gives a good demonstration in terms of the inverse theorem, the theorem of the angle bisector and the inverse theorem, which lays a good foundation for the introduction of the class analogy in this section. Textbook is flat