过椭圆
+=1内一点(0,2)的弦的中点的轨迹方程为( )
A.
+(y−1)2=1B.
+(y−1)2=1C.
+(y−1)2=1D.
+(y−1)2=1
人气:374 ℃ 时间:2019-11-07 14:54:14
解答
设弦两端点坐标为(x1,y1),(x2.y2),诸弦中点坐标为(x,y).弦所在直线斜率为kx2125+y2116=1x2225+ y2216=1两式相减得; 125(x1+x2)(x1-x2)+116(y1+y2)(y1-y2)=0即 2x25+2y16k=0又∵k=y−2x...
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