论文部分内容阅读
初中《几何》第二册P.103给出了切线长定理：从圆外一点引圆的两条切线，它们的切线长相等，圆心和这一点的连线平分两条切线的夹角。
The tangent length theorem of the second book “Geometry” in Volume II. P.103 gives the two tangents drawn from a point outside the circle. Their tangent lengths are equal. The line connecting the center and this point bisects the angle between the two tangents.