在
中,角
的对边分别为
,且
,
,
(1)求角B的大小;
(2)若等差数列
的公差不为零,且
=1,且
成等比数列,求
的前
项和
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4df806de6b8702d37e9256104206ef21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a0c06c2aa2332b71ce32d764975fc84.png)
(1)求角B的大小;
(2)若等差数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://img.xkw.com/dksih/QBM/2016/1/21/1572459094532096/1572459100848128/STEM/6be1519e5e764a1580f17daf31ef6f1a.png?resizew=63)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29b1b845916a4b6a18cdfbcd308d09c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c6c74d1c24b2c8b81cbd6265c7767a0.png)
![](https://img.xkw.com/dksih/QBM/2016/1/21/1572459094532096/1572459100848128/STEM/bd10924f6f7f4897a147817838ad4ac3.png?resizew=13)
![](https://img.xkw.com/dksih/QBM/2016/1/21/1572459094532096/1572459100848128/STEM/c0f16e1b4f01435290515e09dd825a60.png?resizew=20)
更新时间:2016-12-04 01:19:08
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【推荐1】在
中,
.
(1)求
的大小;
(2)若
,求证:
为直角三角形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87e963905c55e7bea7af874fb68ccf19.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3818a2c9919d358b4c3713396093822b.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da8607bde1fa6cde631a46e921d959a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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解题方法
【推荐2】如图所示,甲乙两人站在同一水平面上,与缆车
在同一铅垂平面内且相距50米.假设甲、乙两人的视线处于同一水平线且缆车处于静止状态,甲处观察缆车
的仰角为
,乙处观察缆车
的仰角为
,甲处观察缆车
的仰角为
,乙处观察缆车
的仰角为
.
相对甲乙所在水平面的高度;(结果用
表示)
(2)若测得
,求缆车
之间的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/700458c01a7ad031e27d80ed43e9e882.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4e288596fa3811dd2c17bded60e82e7.png)
(2)若测得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d47cb5378b81fc6b435b631e90587f14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
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【推荐3】某地为响应习总书记关于生态文明建设的指示精神,大力开展“青山绿水”工程,造福于民.为此,当地政府决定将一扇形(如图)荒地改造成市民休闲中心,其中扇形内接矩形区域为市民健身活动场所,其余区域(阴影部分)改造为景观绿地(种植各种花草).已知该扇形
的半径为200米,圆心角
,点
在
上,点
在
上,点
在弧
上,设
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/21/85c99d6c-d967-4672-96b9-0079b783b9ee.png?resizew=399)
(1)若矩形
是正方形,求
的值;
(2)为方便市民观赏绿地景观,从
点处向
修建两条观赏通道
和
(宽度不计),使
,
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依
而建,为让市民有更多时间观赏,希望
最长,试问:此时点
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4819c39c281427826e1b3f7a4c2b720.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc1eb76fe74cba30f7cbcde349ba80da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/259728433d68902065408fb6a34c6d4d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/21/85c99d6c-d967-4672-96b9-0079b783b9ee.png?resizew=399)
(1)若矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/389bc3f29c058067e06e0d0d2be399da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43660b1543b3a2b46185f7629d28a963.png)
(2)为方便市民观赏绿地景观,从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5a5e484dfef494d27bc35ae7b8cf75d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d4aca03910382accfe738520daf689c.png)
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