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平行四边形是一类特殊的四边形,它的两组对边平行且相等,两组对角分别相等,对角线互相平分.平行四边形的每条对角线把它分成两个全等的三角形,两条对角线把平行四边形分成两组全等三角形.平行四边形是中心对称图形,对称中心是对角线的交点.因此,一切位于对称中心两侧的元素都是可证相等的.这一性质是平行四边形的核心性质,是分析有关问题的一个重要依据.
A parallelogram is a special type of quadrilateral whose two opposite sides are parallel and equal. The two sets of diagonals are equal and the diagonals are equally divided. Each diagonal of the parallelogram divides it into two congruent triangles. The two diagonals divide the parallelogram into two sets of congruent triangles. The parallelogram is a centrosymmetric figure, and the center of symmetry is the intersection of the diagonal lines. Therefore, all elements on both sides of the symmetry center are equivalenceable. Nature is the core nature of a parallelogram and is an important basis for analyzing related issues.