1 . 在
中,
(1)已知
,
,
,求
;
(2)已知
,
,
,求
;
(3)已知
,
,
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(1)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99f2f1eb2beb23690f56a68dc7da08cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bbd2d997d89bfb4e06a61a644badb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e258ab9e600435b37465092243d99f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b71812e0762c0aaffb51cfef66156567.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2888481afd63ac64ffd3e4192fae96fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e245411397acbba561c9733b3ec9c55f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6de1d395e6c48c0676a1488a299479d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa04f231b0782d777a39deecf3019297.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
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2 . 海中有一小岛B,周围3.8nmile内有暗礁,军舰由西向东航行到A处,望见岛B在北偏东75°的方向上;军舰又航行了8nmile到达C处,望见岛B在北偏东60°的方向上.若此军舰不改变航向而继续前进,有无触礁危险?
![](https://img.xkw.com/dksih/QBM/2021/11/11/2849052165545984/2849792556670976/STEM/2b7a36b10f1a41b788a4512a0774943e.png?resizew=218)
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20-21高一·全国·课后作业
3 . 如图,作用于同一点
的三个力
,且
,
,
,求
的合力
的大小.(参考数据:
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c25eb4975b46eadd7714bc1923e2998.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbc10a4927d47666847c6ea480e7dd51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1528da09f5a064c5009f206da124e6ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0079c6b4090b677a3718b57e3b577438.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c25eb4975b46eadd7714bc1923e2998.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93dde919c8644b3deeabbde8c7ee7430.png)
![](https://img.xkw.com/dksih/QBM/2021/11/11/2849052165545984/2849792556531712/STEM/8e5f6aab632c4136a4014dd48d1a334f.png?resizew=173)
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20-21高一·全国·课后作业
解题方法
4 . 把一根长为30cm的木条锯成两段,分别作钝角三角形ABC的两边AB和BC且
.如何锯断木条,才能使第三条边AC最短?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e918b70b02a73685e3c536c7f380e2c.png)
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5 . 如图,用两根绳子牵引重为
的物体,两根绳子的拉力分别为
,
,此时平衡.如果
,
与
的夹角
.
的大小(精确到1N);
(2)求
与
的夹角
的值(精确到0.1°).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb0a7565dbb8e665bb691d1de0c73675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3fb78c5f885034612c0e030b920143d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1282962a17a48a18edf733204054d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6773de8f14f06da06bf9c6f22738c6e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3fb78c5f885034612c0e030b920143d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1282962a17a48a18edf733204054d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3bea7383acbd1da6d0d5f10ef1b2aed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1282962a17a48a18edf733204054d67.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1282962a17a48a18edf733204054d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5076289823db419f94e9c0c8f4aafd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
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20-21高一·全国·课后作业
解题方法
6 . 已知△ABC,请用两种方法证明a=bcosC+ccosB(射影定理).
您最近一年使用:0次
20-21高一·全国·课后作业
解题方法
7 . 在△ABC中,内角A,B,C所对的边分别为a,b,c,且满足bsinB=4asinA,bc=2(b2-a2-c2),求B.
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20-21高一·全国·课后作业
8 . 在△ABC中,已知c=
,A=45°,试判断当a分别取10,5,
时,角C的解的个数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa82a15632a545ce2cc6dc998899807.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bee9dfcd07de680b72e34ae38e848086.png)
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20-21高一·全国·课后作业
9 . 在
中,
,
,
,求
,
.(参考数据:
,
;结果取整数)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c14fc2a0082c167da99440b64fe9fe88.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7825c6a2087e562af4d016b63bccf77.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95a2514c2147c1ae20b66462ae7e3b09.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/32b9da385bd721f9341ad900abf0b6d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/205f7667ee4d148aa970cfcd0ee5a334.png)
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