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平行四边形的识别方法较多,有关平行四边形的判定共有五个定理,分别是:两条对角线互相平分的四边形是平行四边形;两组对角分别相等的四边形是平行四边形;两组对边分别平行的四边形是平行四边形;两组对边分别相等的四边形是平行四边形;一组对边平行且相等的四边形是平行四边形。这五个定理其实不难记忆,只要分别按照四边形的基本元素——边、角、对角线来分类就好记了。边、角、对角线是平行四边形的基本元素。由对边相等、
There are five parallelograms. There are five theorems about the judgment of the parallelogram: the quadrilateral whose two diagonals are parallel to each other is parallelogram; the quadrilateral whose two diagonals are equal are parallelogram; Parallel to each other parallelogram is a quadrilateral; two pairs of equal sides of the quadrilateral parallelogram; a parallel and equal sides of the quadrilateral is parallelogram. These five theorems are not hard to remember, as long as they are in accordance with the basic elements of the quadrilateral - edge, angle, diagonal to remember. Edge, corner, diagonal is the basic element of the parallelogram. From the opposite side equal,