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类题推荐
【推荐1】如图,在三棱锥eqIdb55d3c7b977d4b51b0dd9016b5c6f1e8中,eqIde130b83a92ed480b9ef3b28c0cf628a9,侧面eqId4d10816441404717b176af33695dbafd底面eqId89fbdcb029be4482b52165366491c70feqIdadbcad4eca68463fbf9beba120df499feqId0cd8063abf2b458f80091bc51b75a904为线段eqId99a3187c2b8f4bcc9703c74c3b72f1f3上一点,且满足eqId9bda519b9b374ae59f9ddd20b2874ab4.
figure
(1)若eqId93cbffaa5ae045d6ac45d1e979991c3aeqIdcf2da96900c948a1b3ce7cbfd420c080的中点,求证:eqIdfdc492d3e5a44d2e88e0a37a7615cb47
(2)当eqId9dd1d2bdf3d1406c819b69632a9c8e01最小时,求二面角eqId49d9c5fc5d854bf28285460a87fe7fee的余弦值.
难度系数:0.65使用:72次题型:解答题更新:2019/6/20
【推荐2】如图,在几何体eqIdd8df9cbf729648d4af174d66edbe7963中,四边形eqIdbab934511a9f4ec395b9ae92e88107f5为矩形,平面eqId5a16089a89424f6a90815ddfae9eb601平面eqId0645bf529ddb4f81b26e3a3c58a047b5eqId3ebf902415164969955f2167f0c4f5d4平面eqIde37223a82dd14db39016756bd377dd6deqIdab20a825e39545df9a20211f2c591edbeqId93cbffaa5ae045d6ac45d1e979991c3a为棱eqIdea82c30b37894b1bb742dee61200db07的中点.
figure
(Ⅰ)证明:eqId3348af9cf8b442a9ae87ec670e3a09fb平面eqIde1eeae7b5e874850be58d303a386fde9
(Ⅱ)求直线eqIdbd70ef61616a454bae30f5691884094b与平面eqIdf0f4214976bd4e8a868fd23e3cfc3db0所成角的正弦值.
难度系数:0.65使用:110次题型:解答题更新:2019/6/20
【推荐3】已知eqId12175c05cfe240a0b8270ee03df1962f为正三棱锥,底面边长为2,设eqId0cd8063abf2b458f80091bc51b75a904eqIde9b50933e347462ea824ccc9bf51fc93的中点,且eqId3f4d7c2ca35446ab97cc2f02e69cee94,如图所示.
figure
(Ⅰ)求证:eqId534d43b0c6cb404a9201abcafc71f09e平面eqIdfcd3aba6b7804fb68706ce7697ffa7a3
(Ⅱ)求二面角eqId7f2883c746f94fdc85e0ce2c1ef8a3ef的平面角的余弦值.
难度系数:0.85使用:78次题型:解答题更新:2019/6/22
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