如图，菱形ABCD与等边△PAD所在的平面相互垂直，AD=2，∠DAB=60°．（Ⅰ）证明：AD⊥PB；（Ⅱ）求三棱锥C﹣PAB的高．

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如图，菱形ABCD与等边△PAD所在的平面相互垂直，AD=2，∠DAB=60°．

（Ⅰ）证明：AD⊥PB；

（Ⅱ）求三棱锥C﹣PAB的高．

上一题下一题 0.0难度选择题更新时间:2018-02-09 02:02:06

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（Ⅰ）证明：取AD中点O，连结OP、OB、BD，∵菱形ABCD与等边△PAD所在的平面相互垂直，AD=2，∠DAB=60°．∴OP⊥AD，BO⊥AD，∵OP∩BO=O，∴AD⊥平面POB，∵PB⊂平面POB，∴AD⊥PB．（Ⅱ）解：法一：∵菱形ABCD与等边△PAD所在的平面相互垂直，AD=2，∠DAB=60°．∴BO=PO=

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Welcome to our school. Our school is on Xianyang Street. It’s next to the Xinhua Library. There is a big garden across from our school. The payphone is between our school and the post office. There are three buildings in our school, the students' building, the teachers'building and a library. The teachers in our school are good. Our school yard is very beautiful. If you come to our school from the airport, take a taxi and go along the highway until you see a bridge. Go across the bridge and turn left. Then go straight along the Bridge Street. Our school is on the right.

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