欲证“a~2=bc”类题,一般采用相似法,其实还有代换法、三角法、圆幂法和面积法等等.有些题目形似复杂,但通过仔细观察和分析(图形和题设),把所学知识融汇贯通起来,充分挖掘隐含条件,选用适当的方法,解题就不十分困难了.现举例说明解题方法的应用. In order to prove that the “a~2=bc” class question, similar methods are generally used. Actually there are substitution method, trigonometry, circular power method, area method, etc. Some of the topics are complex but they are carefully observed and analyzed ( The graphics and the title design) integrate the knowledge learned, fully explore the hidden conditions, select the appropriate method, and solve the problem is not very difficult. Now illustrate the application of the problem solving method.