已知向量 a =(x, 2 y), b =(1,0) ,且 ( a +2 b )⊥( a -2 b ) .点T(x,y) (1)求点T的轨迹方程C; (2)过点(0,1)且以 (2, 2 ) 为方向向量的一条直线与轨迹方程C相交于点P,Q两点,OP,OQ所在的直线的斜率分别是k OP 、k OQ ,求k OP ?k OQ 的值.
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