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一、两知1.知切线的三种判定方法一条直线满足下列条件中的任一条,这条直线就是圆的切线. (1)直线和圆有惟一公共点; (2)圆心到直线的距离等于圆的半径; (3)经过直径一端,并且垂直于这条直径.
One, two know 1. Know the three methods of tangent Determination of a straight line to meet any one of the following conditions, this line is the tangent of the circle. (1) The straight line and the circle have a single common point; (2) Center-line distance Equal to the radius of the circle; (3) pass through one end of the diameter and perpendicular to this diameter.