y=√2sinx/(2-cosx)y(2-cosx)=√2sinx√2sinx+ycosx=2y√(2+y²)sin(x+∅)=2ysin(x+∅)=2y/√(2+y²)∴ |2y/√(2+y²)|≤1∴ |2y|≤√(2+y²)∴ 4y²≤2+y²∴ 3y²≤2∴ 值...