近几年来,涉及圆锥曲线切线的试题很多,主要是求切线方程、研究切线的性质、切线的应用等几类问题.探究圆锥曲线的切线作法有利于理解圆锥曲线的本质属性,迅速发现解题思路,提高分析问题、解决问题的能力.以下举3例说明.例1(2012年高考福建理科卷)如图 In recent years, there are many questions concerning the tangent of conic curve, such as finding the tangent equation, studying the nature of the tangent, the application of tangent, etc. It is helpful to understand the essential properties of the conic and explore the solution of the problem Ideas, improve the analysis of the problem, the ability to solve the problem. The following three cases illustrate. Example 1 (Fujian college entrance examination in 2012 volumes) as shown