椭圆上有两点P、Q,O为坐标原点,且有直线OP,OQ的斜率满足kop×koq=-1/2 求线段PQ中点的轨迹方程.

设参数方程 P（Acosa,Bsina）Q(Acosb,Bsinb) Kop=Btana/A Koq=Btanb/A
B^2tanatanb/A^2=-1/2 PQ终点坐标（Acosa/2+Acosb/2,Bsina/2+Bsinb/2）x^2=A^2/4(cosa+cosb)^2 y^2=B^2/4(sina+sinb)^2