正在做啊设直线AB的斜率为k (a为直线AB的倾斜角)当a=π/2时,AB垂直于x轴，x=p/2得y=±p所以AB的坐标分别为(p/2,p),(p/2,-p)y1*y2=-p^2,x1*x2=p^2/4当a≠π/2y^2=2px焦点(p/2,0),准线x=-p/2则直线AB：y=k(x-p/2)抛物线：y^2=2px 联立k^2x^2-(k^2p+2p)x+k^2*p^2/4=0则x1*x2=p^2/4联立消去x得到y^2=2p(y/k+p/2)y^2-2p/k y-p^2=0则有y1y2=-p^2