有些几何问题 ,往往可以用面积法来解决 .面积法解几何问题常用到下列性质 :性质 1　等底等高的三角形面积相等 ;性质 2　同底等高的三角形面积相等 ;性质 3　三角形面积等于与它同底等高的平行四边形面积的一半 ;性质 4　等高的两个三角形的面积比等于底之比 ;性质 5　等底的? Some geometric problems can often be solved by the area method. The area method solves the geometric problems commonly used to the following properties: Nature 1 Equal contour triangle area is equal; Nature 2 Same height contour triangle area is equal; Nature 3 Triangle area equals to It is half the area of ​​the parallelogram with the same height; the ratio of the area ratio of the two triangles of the nature 4 is equal to the bottom; the property 5 is equal to the bottom?