解题方法
1 . 一块三棱锥形状的余料
,其三条侧棱
,
,
两两垂直.现需将其切割成直三棱柱,使得直三棱柱的侧棱与原三棱锥的一条侧棱平行或重合.若
,
,
,则切割得到的直三棱柱的最大体积为___________ ;不失一般性,若
,
,
,则切割得到的直三棱柱的最大体积为___________ .(结果用
,
,
表示,其中
,
,
为正实数).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00bab2c27eac56fffa4cd7dbe1dcdf1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89b336e518ac4ff04c6c26e4b8a15844.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eea78bf026d76f1cb9cc3dc9349a193.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00803e67a5d417a9a4dc00277fca778b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/495636df02b96acab4478baabe77bafa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69acd73890957b0007b30fd81f2abc0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
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解题方法
2 . 元旦期间某牛奶公司做促销活动.一箱某品牌牛奶
盒,每盒牛奶可以参与刮奖中奖得现金活动,但其中只有一些中奖.已知购买一盒牛奶需要
元,若有中奖,则每次中奖可以获得代金券
元(可即中即用).顾客可以在一箱牛奶中先购买
盒,然后根据这
盒牛奶中奖结果决定是否购买余下
盒.设每盒牛奶中奖概率为
,且每盒牛奶是否中奖相互独立.
(1)若
,顾客先购买
盒牛奶,求该顾客至少有一盒中奖的概率;
(2)设先购买的
盒牛奶恰好有一盒中奖的最大概率为
,以
为
值.某顾客认为如果中奖后售价不超过原来售价的四折(即
)便可以购买如下的
盒牛奶,据此,请你判断该顾客是否可以购买余下的
盒牛奶.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8da45c443af7994a26ffa9d8894e7262.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d91e07104b699c4012be2d26160976a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3304e23f3b0f9569c4140ca89b6498.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3304e23f3b0f9569c4140ca89b6498.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29c8578f06897aa6fb84aa95c797d3d8.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dd2bb6c784518b0a063b751e6009188.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
(2)设先购买的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3606c4a853a6a34cb7f33bea81b15a1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3606c4a853a6a34cb7f33bea81b15a1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8af17034249858aca29b51a359a672c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3304e23f3b0f9569c4140ca89b6498.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3304e23f3b0f9569c4140ca89b6498.png)
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