直线与圆的位置关系是《圆》中的重点内容.其中,切线的性质用法灵活,与其他图形的组合多变.若将相关的图形作一些比较归纳,顺着切线条数的思路,可以使很多问题得到系统的解决.一、已知一条直线和圆相切可以得到三个结论:1.圆心与切点的连线垂直于切线.这是切 The relationship between the line and the circle is the key point in the circle, in which the nature of the tangent is flexible and can be changed in combination with other figures. If the related figures are compared and summarized, along the line of tangent, So that many problems are systematically solved. First, it is known that a straight line tangent to the circle can get three conclusions: 1. The center of the line and the tangent point of the connection perpendicular to the tangent. This is cut