Re: [中學] 空間向量 1題

[Honor1984 (奈何上天造化弄人？)]

※ 引述《hero010188 (我是海賊王)》之銘言：
: https://i.imgur.com/g5tyovY.jpeg
: 感謝

令AE = k

AC * (AD + k) = 0

=> AD * AC + k * AC = 0

(AD + k) * (AB + k) = -1

=> |k|^2 + k * AC + AB * AD = -1

=> |k|^2 = -1 + AD * AC - AB * AD

         = -1 + 3 = 2

選(2)

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推 hero010188  : 感謝!