过抛物线y2=2px(p>0)的焦点F作倾斜角为45°的直线交抛物线于A、B两点,若线段AB的长为8,则p=______

2025-04-09 02:21:01
推荐回答(1个)
回答1:

由题意可知过焦点的直线方程为y=x?

p
2

联立有
y2=2px
y=x?
p
2
?x2?3px+
p2
4
=0

∴x1+x2=3p,x1x2=
p2
4

∴|x1-x2|=
(x1+x2)2?4x1x2
=
(3p)2?4×
p2
4

|AB|=
(1+12)
(3p)2?4×
p2