数学方法众多,解法不同,所涉及的运算量也不同,快速有效地解题更是考生制胜的法宝.运用平行转换法求三角形的面积是常见的实用方法.它的基本原理如图1:当AB与CD平行时,△ABC和△ABD同底等高,S_(△ABC)=S_(△ABD).也就是借助平行线将S_(△ABC)转换为S_(△ABD),或者说将点C转换为点D.它的特点是可以减少运算量,快速计算三角形面积. Many mathematical methods, solutions are different, the amount of computation involved is also quick and effective solution to the problem is to test the winning magic. The use of parallel conversion method to find the area of ​​the triangle is a common practical method. Its basic principle shown in Figure 1: When AB and CD parallel, △ ABC and △ ABD with the same base, S_ (△ ABC) = S_ (△ ABD). That is, by parallel lines will be S_ (△ ABC) is converted to S_ Point C is converted to point D. It is characterized by the amount of computation can be reduced quickly calculate the area of ​​the triangle.