四边形
来勒几何学中，四边形是指有四条边搭四个顶点个多边形，其内角和为360度。四边形有交关多种，其中对称性顶顶高个是正方形，其次是长方形或菱形，较低对称性个四边形如等腰梯形搭鹞形，对称轴只有一条。其他个四边形依照其类角个性质可以分成凸四边形搭非凸四边形，其中凸四边形代表所有内角角度皆小于180度。非凸四边形可以更加进一步分成凹四边形搭复杂四边形，其中复杂四边形表示边自我相交个四边形。
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