如图,在三棱锥B-ACO中,BO、AO、CO所在直线两两垂直,且AO=CO,∠BAO=60°,E是AC的中点,三棱锥B-ACO的体积为
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.
(1)求三棱锥B-ACO的高;
(2)在线段AB上取一点D,当D在什么位置时,
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和
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的夹角大小为arccos
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.
考点分析:
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已知复数z
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