两圆相切的判定及应用

• 作 者: 吴远宏
• 机 构: 辽宁省大连市三洋压缩机有限公司,
• 出 处: 中学生数学
• 发表日期: 2012年22期
• 关键词: 两圆相切 两圆内切 切线法 圆心距 公共点 异侧 辽宁省大连市 三点共线 应用举例 吴远

初中教科书在介绍圆和圆的位置关系时,给出了两圆相切的判定方法,即:设两圆的半径分别为R和r,圆心距为d,若d=R+r,则两圆外切;若d=R-r(R>r),则两圆内切.本文不妨统称为“圆心距法”.下面介绍另一种判定方法,这里统称为“公切线法”.一、两圆相切的判定1.两圆外切的判定过两圆的公共点作

Junior high school textbooks in the introduction of the relationship between the location of the circle and gives the two rounds of tangent to determine the method, that is: Let the two circles were R and r, the center distance is d, if d = R + r, then the two Circle circumcision; if d = Rr (R> r), the two circles are inscribed. This article may be collectively referred to as “circle center distance method.” Here is another way to judge, here collectively referred to as “public tangent method” First, the two rounds of the tangent of the decision 1. Two rounds of circumscribed two public points