用面积法证明几何问题,关键在于建立所证元素与有关图形的联系。一些看起来与面积“无关”的问题,一旦与面积联系起来,用“面积法”来解决就格外简明。下面举例说明。一、证角相等例1如图1,在平行四边形ABCD的两边AD和CD上各取一点F和E,若AE=CF,且相交于点P.求证:∠APB=∠CPB.分析:根据角平分线的性质, The use of area method to prove geometric problems, the key lies in establishing the connection between the elements of the proof and the relevant graphics. Some problems that seem to have nothing to do with the area, once they are related to the area, are more concise with the “area method.” The following is an example. First, the agreement angle example 1 In Figure 1, in the parallelogram ABCD on both sides AD and CD take a point F and E, if AE = CF, and intersect at the point P. Proof: ∠APB = ∠ CPB. Analysis: According to The nature of the angle bisector,