这道题很难（加分!）,要用到图形结合法.先由a=2b有n+2=2m和n²-cos²t=m+2sint,对于后式两边加1并整理得f(sint)=sin²t-2sint+n²-m-1=0.∵t为实数,∴sint必须有意义,即-10,1-2+n²-m-1≤0.整理...