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用矢量，内积为0根据条件就可以了P,Q的坐标用(x1,-x1-1),(x2,-x2-1)则x1x2+x1x2+x1+x2+1=0.....(*)a^2=2c^2,b^2=c^2x1^2/2c^2+y1^2/c^2=1.....(1)x2^2/2c^2+y2^2/c^2=1......(2)(2)-(1)(x1^2-x2^2)/2c^2+(y1+y2)(y1-y2)/c^2=0(x1^2-x2^2)/2c^2+(-x1-x2-2)(x2-x1)/c^2=0....(3)由(*),(3)((x1-x2)(1.5(x1+x2)+2))/c^2=0即：(x1-x2)(1.5(x1+x2)+2)=0.....( |
