大家知道,若方程f(x)=0的根为m,则有f(m)=0,反之,若f(m)=0,则m是方程f(x)=0的根,本文就此问题谈谈如何逆用方程根的定义解决解析几何问题,希望能引起同学们的注意.例1已知a2sinθ+acosθ-1=0,b2sinθ+bcosθ-1=0,a≠b.证明:过点(a,a2),(b,b2)的直线恒与单位圆相切.证明过(a,a2) We all know that if the root of the equation f(x)=0 is m, then f(m)=0, otherwise, if f(m)=0, then m is the root of the equation f(x)=0. The question talks about how to inversely use the definition of the equation root to solve the analytical geometry problem, hoping to arouse the attention of the students. Example 1 It is known that a2sinθ+acosθ-1=0, b2sinθ+bcosθ-1=0, a≠b. Prove that: The straight lines of points (a, a2), (b, b2) are always tangent to the unit circle. Proof (a, a2)