過橢圓x^2/4+y^2/3=1的右焦點F2作一傾斜角為派/4的直線交與該橢圓與A\B兩點.求:弦AB的長

過橢圓x^2/4+y^2/3=1的右焦點F2作一傾斜角為派/4的直線交與該橢圓與A\B兩點.求:弦AB的長

a^2=4,b^2=3,c^2=a^2-b^2=1,F2(1,0),k=tana=1,方程y=x-1,代入橢圓方程得x^2/4+(x-1)^2/3=1,化簡得7x^2-8x-8=0.設A(x1,y1),B(x2,y2),則x1+x2=8/7,x1*x2=-8/7,所以|AB|^2=(x2-x1)^2+(y2-y1)^2=2(x2-x1)^2=2…