在人教版九年级数学“圆”一章中,关于弧、弦、圆心角之间的关系有这样一个定理:在同圆或等圆中,如果两条弦相等,那么它们所对的圆心角相等,所对的弧也相等.笔者认为这个定理表述的不够严谨,应该进行修改.因为弧有劣弧和优弧之分,一条不经过圆心的弦所对的弧可以是劣弧,也可以是优弧,所以在同圆 In PEP 9th grade mathematics, the chapter “Roundness” has a theorem about the relationship between arcs, strings, and central angles. In the same circle or circle, if the two strings are equal, then what they are The center angle of the circle is equal and the arcs are equal.I think this theorem is not rigorous and should be modified.As the arc has a bad arc and the arc of the cent, an arc without the center of the arc can be a poor arc , Can also be excellent arc, so in the same circle