1 . 圆锥是生活中常见的立体图形,如雪糕筒,漏斗,羽毛球,路障等,赵亮同学用一个如图①所示的扇形围成如图②所示的圆锥,
为圆锥的高,点D为母线
上的中点,
,
为底面圆半径,
,求图①中
的长度.(参考数据:
取
,
,
)
解:如图②,因为
,所以
,
因为在
中,点D为
边中点,
,
所以
(__________)(填推理依据),
_________(填“
”或“
”).
如图①,所以
_______(填相应的三角形函数值)
________(
)(结果精确到
).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df24e3f6b801f1f499782b1721b7204c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a15c8816ec5571bea8b14107dafced0f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d65cecaf8a3dc2953f4109c75a981e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60e0d7dc5260d13fd62425ee75fcca96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/868d4cc71c2bcfa5cc8dc8b0b92c00de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5241fdf84918d9b59b48888cff38378.png)
解:如图②,因为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/451156790ac81457a25bdfa06d867233.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c94f9780b3992d0c10deecbe237b68fa.png)
因为在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c1636b112636047c1986661467ee3ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f93f9f6f69927d47033ec9ead50fde5.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/206f53a13ad4cb176354def154201d9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d59a9484d847166f3373020ec49fc232.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7919ab521e6390134305166aaad3d658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316e85517919c422ecd81c95fb367d57.png)
如图①,所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8098660fbba570f47395a48d385fbf65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a579867933f05906dc5687d52bf77ac3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e15e00f40396e914d1d9955bd7785f1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfaa19eeaf415ed419e77fe92794f443.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/19/71366b3a-c15d-49e4-afb2-e884434f18bb.png?resizew=262)
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2 . (1)解方程:
;
(2)已知一个圆锥的母线长为
,底面圆的半径为
,求这个圆锥的侧面展开图扇形的圆心角的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e758ff84ef212246e8dbf4e26a38d296.png)
(2)已知一个圆锥的母线长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
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3 . 为落实好扶贫工作,某村驻村干部帮助村民修建了一个粮仓,该粮仓的屋顶是一个圆锥,为了合理购买、不浪费原材料,需要进行计算1个屋顶的侧面积大小,该圆锥母线长为5m,底面圆周长为
,则1个屋顶的侧面积等于( )
.(结果保留
)
![](https://img.xkw.com/dksih/QBM/2020/12/9/2610453030109184/2614599864868864/STEM/8eebd29f-8dab-4c52-8f50-d651b872523b.png?resizew=120)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94a36db61f455d4a1814cc64fa57fbe1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35c901bcdfa58f0c68ad0161b0bab269.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
![](https://img.xkw.com/dksih/QBM/2020/12/9/2610453030109184/2614599864868864/STEM/8eebd29f-8dab-4c52-8f50-d651b872523b.png?resizew=120)
A.![]() | B.![]() | C.![]() | D.![]() |
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4 . 如图,
是
的直径,C、D为
上的点,点E在
的延长线上,直线
经过点C,已知
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/23/2d655be5-a1b9-4653-8f04-618b6ebb190f.png?resizew=179)
(1)求证:
为
的切线.
(2)若
,
的半径等于
,求
绕
旋转一周得到的几何体的表面积(结果保留
).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c631670e02d2a38e9c78708a3916140.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd8239c1ba05a423901c4f4e84e8871a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/23/2d655be5-a1b9-4653-8f04-618b6ebb190f.png?resizew=179)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1e0b41cd45fba881194a02ec19bc26e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95bacae35b6e16a0a33c2bdc6bc07df7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70f5389990c3a0c5373f3bd9fb2454c9.png)
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