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如图,在四棱锥P-ABCD中,PA⊥面ABCD,AB=BC=2,AD=CD=
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,PA=
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,∠ABC=120°,G为线段PC上的点.
(Ⅰ)证明:BD⊥平面PAC;
(Ⅱ)若G是PC的中点,求DG与PAC所成的角的正切值;
(Ⅲ)若G满足PC⊥面BGD,求
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的值.
考点分析:
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在锐角△ABC中,内角A,B,C的对边分别为a,b,c,且2asinB=
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b.
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设
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、
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为单位向量,非零向量
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=x
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