焦点F(p/2,0)设弦所在直线斜率为k,方程为y = k(x - p/2),x = y/k + p/2y² = 2p(y/k + p/2) = 2py/k + p²ky² -2py - kp² = 0y = [p ± p√(k² + 1)]/kx = [p ± p√(k² + 1)]/k² ...为什么y＝k﹙x－p／2﹚标准形式为y2=2px时，焦点为(p/2, 0), 准线为x = -p/2