等式左边:(m^2-n^2)^2=[(m+n)(m-n)]^2=[2tana*2sina]^2=16tan^2(a)*sin^2(a)=16sin^4(a)/cos^2(a).等式右边:16mn=16*[tan^2(a)-sin^2(a)]=16[sin^2(a)]*[1-cos^2(a)]/cos^2(a)=16*sin^4(a)/cos^2(a).=右边,即,:(m^2-...