抛物线的顶点是坐标原点,对称轴是坐标轴,集点在X轴上,则抛物线可表达为y² =2px或y² = -2px,p >0
前者的焦点为(p/2,0),直线L:x = p/2
代入y² =2px,y² =2p*p/2= p²,y = ±p
A(p/2,-p),B(p/2,p)
|AB| = 2p=6
p = 3
y² = 6x
类似地,另一解为y² = -6x