构造法就是从问题的结构和特点出发 ,进行广泛联想 ,构造一个与问题相关的数学模型 ,实现问题的转化 ,从而解决问题的方法 .构造等差、等比数列是解决三角问题的一种有效方法 .下面举例加以说明 .1　构造等差数列例 1　 (2 0 0 4年北京市高考题 )在△ABC ,sinA+cosA =22 ,求tan The construction method starts from the structure and characteristics of the problem, makes a broad association, constructs a mathematical model related to the problem, realizes the transformation of the problem, and thus solves the problem. Constructing arithmetic and geometric arrays is an effective solution to the triangular problem. Methods. The following examples are used to illustrate. 1 Constructing an arithmetic progression example 1 (Beijing 2008 college entrance examination question) in △ABC, sinA+cosA = 22, seeking tan