X^2/25+Y^2/9=1,a=5,b=3,c=√(a^2-b^2)=4.则F1坐标为(-4,0),F2坐标为(4,0).设,点P坐标为(m,n).PF1的斜率为K1=n/(m+4),PF2的斜率为K2=n/(m-4).而,K1*K2=-1,n^2/(m^2-16)=-1.而,点P(m,n)在椭圆上,有m^2/25+n^2/9=1,m^2...