换元法是一种十分重要的思想方法,而其中三角换元更是应用广泛.三角换元法主要利用已知代数式中与三角知识中有某点联系进行换元,对于解决某些函数、方程以及不等式等问题有着出奇的效果,特别是对一些无理函数,三角换元显得举足轻重,用得好可以让我们做题事半功倍. The equivalence method is a very important method of thought, and the triangular ones are widely used. The triangular merging method mainly uses a certain point in the known algebraic formulas to associate with the trigonometry knowledge to perform the equivalence, to solve certain functions, Problems such as equations and inequalities have surprising effects, especially for some irrational functions, trigonometric ones appear to be important, and well used allows us to do more with less.