已知m、n是兩條不重合的直線,α、β是兩個(gè)不重合的平面,下列命題中正確的是( )
A.若m∥α,n∥β,α∥β,則m∥n | B.若m∥n,nÌα,m(/α,則m∥α |
C.若α⊥β,m⊥α,則m∥β | D.若m⊥α,nÌβ,m⊥n,則α⊥β |
試題分析:對于A,平行于兩個(gè)平行平面的兩條直線未必平行,對于B,根據(jù)線面平行的判定定理進(jìn)行判定即可,對于C,直線m可能在平面β內(nèi),對于D,平面α與平面β可能平行,從而得到結(jié)論解:對于A,平行于兩個(gè)平行平面的兩條直線未必平行,因此A不正確;對于B,由“平面外一條直線平行于平面內(nèi)的一條直線,則該直線平行于該平面”,因此B正確;對于C,直線m可能在平面β內(nèi),因此C不正確;對于D,平面α與平面β可能平行,因此D不正確.故選B
點(diǎn)評:本題主要考查了空間中直線與平面之間的位置關(guān)系,考查學(xué)生空間想象能力,邏輯思維能力,是中檔題
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.
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;
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與平面
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中,底面
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是直角梯形,
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,
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.
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(1)求證:
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平面
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,使得
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與平面
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