我们知道,一个命题可以有四种不同形式,其中,原命题“若p,则q”与逆否命题“若■q,则■p”是等价命题;逆命题“若q,则p”与否命题“若■p,则■q”也是等价命题.这为数学问题的证明提供了一种新的等价转化的途径:当证明原命题有困难时,变换角度,探索它的 We know that a proposition can have four different forms, where the original proposition “if p, then q” and the inverse no proposition “ifq, then p” are equivalent propositions; the reverse proposition “if q, then p ”whether or not proposition“ if p, then q ” is also an equivalent proposition. This provides a new way of equivalent transformation for the proof of mathematic problems: when it is difficult to prove the original proposition , transform the angle, explore it