随风2825
幼苗
共回答了14个问题采纳率:78.6% 举报
1.a=2
e=c/a,c=ae=2*√3/2=√3
c²=a²-b²,b=1
x²/4+y²=1
2.设C(x,y),则Q(x,0)
|PQ|=|PC|,则P(x,y/2)
又x²/4+y²=1,所以C点坐标的轨迹:x²/4+(y/2)²=1,x²+y²=4
3.设C(x0,y0),x0²+y0²=4
K=(y0-0)/(x0+2)=y0/(x0+2)
直线AC:y=y0/(x0+2)x+b,经过(-2,0),0=y0/(x0+2)*(-2)+b,b=2y0/(x0+2)
AC:y=y0/(x0+2)(x+2)
令 x=2,y=4y0/(x0+2),则 R(2,4y0/(x0+2)),D(2,2y0/(x0+2))
CD的斜率k1=[2y0/(x0+2)-y0]/(2-x0)=x0y0/[(x0+2)(x0-2)]
设CD的方程:y=k1x+b1,经过C(x0,y0),y0=x0y0x0/[xo+2)(x0-2)]+b,b=-4y0/(x0²-4)
则 y=x0y0/(x0²-4)x-4y0(x0²-4)=x0y0/y0²x-4y0/y0²=x0/y0x-4/y0
xox-y0y=4
1年前
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