同学们都知道，由平行四边形的性质可知，利用平行四边形可以证明两条直线平行、两条线段相等、两个角相等或两条线段互相平分．因此，在几何证题中，若遇到上述类型的证明题，则可考虑利用平行四边形给出证明．如果给定图形中没有可供利用的平行四边形，那么应该添加适当的辅 As the classmates know, the nature of parallelograms shows that parallelograms can be used to prove that two lines are parallel, two lines are equal, two angles are equal, or two line segments are equally divided. Therefore, in the geometrical proof, if we encounter the above-mentioned types of proofs, we can consider using parallelograms to give proofs. If there are no parallelograms available for use in a given graph, appropriate supplements should be added