圆x^2+y^2-2x-1=0关于直线2x-y+3=0对称的圆的方程是( )A.(x+3)^2+(y-2)^2=1/2B.(x-3)^2+(y+2)^2=1/2C.(x+3)^2+(y-2)^2=2D.(x-3)^2+(y+2)^2=2
问题描述:
圆x^2+y^2-2x-1=0关于直线2x-y+3=0对称的圆的方程是( )
A.(x+3)^2+(y-2)^2=1/2
B.(x-3)^2+(y+2)^2=1/2
C.(x+3)^2+(y-2)^2=2
D.(x-3)^2+(y+2)^2=2
答
x^2+y^2-2x-1=0
配方得x^2+(y-1)^2=2
所以圆心为(0,1),半径√2
圆x^2+y^2-2x-1=0关于直线2x-y+3=0对称的圆
圆心为(-3,2),半径√2
所以方程为(x+3)^2+(y-2)^2=2
即x^2+y^2+6x-4y+11=0