f(x)=sin²x+acosx-(1/2)a-(3/2)=1-cos²x+acosx-(1/2)a-(3/2)=-cos²x+acosx-(1/2)a-(1/2)=-(cosx-a/2)²+(a²-2a-2)/4(1) 当-1≤a/2≤1,即-2≤a≤2时cosx=a/2取到最大值(a²-2a-2)/4=1a&#...确定是对的么...已验算确认