相切的

例句：

1. 1. Thetangent of a circle is the lengthof its circumference.
   圆的切线是其周长的长度。
2. 2.The tangent to the curve at pointA is perpendicular to theline segment joining points A and B.
   曲线在点A处的切线与连接点A和B的线段垂直。
3. 3.The tangent to the circle at pointC is the radius of the circle.
   圆在点C处的切线是圆的半径。