根号下(AB^2-BC^2)=AC
计算是可以把(m^2+n^2）-(m^2-n^2)化简成(m^2+n^2+m^2-n^2)((m^2+n^2-m^2+n^2)=4m^2n^2
再开根号 就等于2mn谢谢，但请你把过程写清楚点利用勾股定理AB=m^2+n^2AB^2=(m^2+n^2)^2BC=m^2-n^2BC^2=(m^2-n^2)^2AB^2-BC^2=(m^2+n^2)^2-(m^2-n^2)^2=(m^2+n^2+m^2-n^2)(m^2+n^2-m^2+n^2)=4m^2n^2再开根号 就等于2mn=AC刚才忘了写上平方