“设而不求法”亦称“增设辅助未知量法”或“设参法”.解题时通常先设辅助元,再利用其与未知量之间的制约关系,建立方程或代数式,然后将未知数消去或代换以解决问题.此法不仅广泛运用于代数问题中,而且在几何问题中也有应用.下面举例说明设而不求法在解有关三角形的几何问题中的应用. “Set without seeking ” also known as “Auxiliary unknowns ” or “set parameters. ” Problem-solving usually first set auxiliary elements, and then use its relationship with the unknowns, the establishment of Equations or algebraic equations, and then eliminate or replace the unknowns to solve the problem.This method is not only widely used in algebraic problems, but also in the geometric problems are also used to illustrate the following examples without seeking solutions to the geometric problems related to the triangle .