3sin^2α+2sin^2β=2sinα所以2sin^2α+2sin^2β=2sinα-sin^2α令cos^2α+cos^2β=E则4-2A=2sinα-sin^2αA=(4-2sinα+sin^2α)/2=[(sinα-1)^2 +3]/2又sinα 属于[-1,1](sinα-1)属于[-2,0](sinα-1)^2属于[0,4][(...