Question

在三角形ABC中,a=m平方-n平方,b=m平方+n平方,当C=什么时,角B=90度

Answer 1

c^2=(m^2+n^2)^2-(m^2-n^2)^2 c^2=m^4+n^4+2m^2n^2-(m^4+n^4-2m^2n^2) c^2=2m^2n^2+2m^2n^2 c^2=4m^2n^2 c=2mn