设过F且倾斜角是45度的一条直线方程是y=x+c.代入到椭圆方程中有(y-c)^2/a^2+y^2/b^2=1b^2(y^2-2cy+c^2)+a^2y^2=a^2b^2(a^2+b^2)y^2-2b^2cy+b^2c^2-a^2b^2=0y1+y2=2b^2c/(a^2+b^2)y1y2=b^2(c^2-a^2)/(a^2+b^2)=-b^4/(...
设过F且倾斜角是45度的一条直线方程是y=x+c.代入到椭圆方程中有(y-c)^2/a^2+y^2/b^2=1b^2(y^2-2cy+c^2)+a^2y^2=a^2b^2(a^2+b^2)y^2-2b^2cy+b^2c^2-a^2b^2=0y1+y2=2b^2c/(a^2+b^2)y1y2=b^2(c^2-a^2)/(a^2+b^2)=-b^4/(...