在直线与圆的位置关系中,直线与圆相切时求切线方程和相交时研究与弦长有关的问题是两个重点内容.1.求切线时,若知道切点,则可直接利用公式:(1)若点(x0,y0)在圆x2+y2=r2上,则切线方程为 In the positional relationship between the straight line and the circle, the tangent equation for tangent to the circle and the problem related to studying the chord length when intersecting with each other are two important contents. 1. When the tangent line is known, if you know the tangent point, you can use the formula directly. : (1) If the point (x0, y0) is on the circle x2+y2=r2, the tangent equation is