等比定理“b/a=c/d=…=m/n(?)(a+c+…+m)/(b+d+…+n)=a/b”是平几里成比例的线段一节的定理。其中字母 a、b、c、d、…m、n 都表示线段,属正实数,和式“a+c+…+m”与“b+d+…+n”也表示线段,亦为正实数。如果我们将定理中各元素所属范围加以扩充,不难证明:当 a、b、c、d、…m、n 及 a+c+…+m,b+d+…+n 均为非零实数时,定理依然成立。这样,定理便可广泛应 The equal-ratio theorem “b/a=c/d=...=m/n(?)(a+c+...+m)/(b+d+...+n)=a/b” is a line segment that is proportional to a few miles The theorem of the section. The letters a, b, c, d, ..., m, n all represent line segments, which are positive real numbers, and the expressions “a+c+...+m” and “b+d+...+n” also indicate line segments, which are also positive real numbers. If we extend the scope of the elements in the Theorem, it is not difficult to prove: When a, b, c, d, ...m, n and a+c+...+m, b+d+...+n are all nonzero real numbers, The theorem still holds. In this way, the theorem can be widely applied