m:y=k1x+b过m(-2,0)
m:y=k1x+2k1
代入椭圆,得:
(2k1^2+1)x^2+8k1^2x+8k1^2-2=0
x1+x2=-8k1^2/(2k1^2+1)
由定必分点公式得:
P(x,y)
x=(x1+x2)/2=-4k1^2/(2k1^2+1)
y=(y1+y2)/2=k1(x1+x2+4)/2=2k1/(2k1^2+1)
OP斜率K2,过P点
y=k2×x,代入P
k1k2=-1/2
m:y=k1x+b过m(-2,0)
m:y=k1x+2k1
代入椭圆,得:
(2k1^2+1)x^2+8k1^2x+8k1^2-2=0
x1+x2=-8k1^2/(2k1^2+1)
由定必分点公式得:
P(x,y)
x=(x1+x2)/2=-4k1^2/(2k1^2+1)
y=(y1+y2)/2=k1(x1+x2+4)/2=2k1/(2k1^2+1)
OP斜率K2,过P点
y=k2×x,代入P
k1k2=-1/2