1、有A,B两点坐标得AB方程为,bx-ay-ab=0,原点到AB直线距离公式得
ab/√(a²+b²)=2√3/3.即ab/c=2√3/3,又c/a=e=2√3/3,解得b=4/3,a²=16/3,
曲线方程为x²/(16/3)-y²/(16/9)=1.
2、 设C(x1,y1),D(x2,y2),将直线方程带入曲线方程得(3-9k²)x²-90kx-241=0,有韦达定理得x1+x2=90k/(3-9k²),y1+y2=k(x1+x2)+10=30/(3-9k²),
CD中点H(45k/(3-9k²),15/(3-9k²)),由题意得BH和CD垂直.即二者斜率之积为
-1.即15/(3-9k²)+4/3=-1/k×(45k/(3-9k²)),解得k=±4√3/3.