设实数x,y满足x*x +(y-1)(y-1)=1,若对满足组条件的x,y,x+y+c≥0恒成立,则c的取值范围是.

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设实数x,y满足x*x+(y-1)(y-1)=1,若对满足组条件的x,y,x+y+c≥0恒成立,则c的取值范围是.设实数x,y满足x*x+(y-1)(y-1)=1,若对满足组条件的x,y,x+y+c≥

设实数x,y满足x*x +(y-1)(y-1)=1,若对满足组条件的x,y,x+y+c≥0恒成立,则c的取值范围是.
设实数x,y满足x*x +(y-1)(y-1)=1,若对满足组条件的x,y,x+y+c≥0恒成立,则c的取值范围是.

设实数x,y满足x*x +(y-1)(y-1)=1,若对满足组条件的x,y,x+y+c≥0恒成立,则c的取值范围是.
令X=sina,Y=cosa+1,则X+Y+c=sina+cosa+1+c ≥根号2×sin(a+pai/4)+1+c ≥0 于是c ≥-1-根号2×sin(a+pai/4) {注意sin∈{-1,1}取最小值} ≥-1+根号2 所以c≥-1+根号2