费马点是在三角形中到三个顶点距离之和最小的点.具体位置取决于三角形的形状,如果三角形的三个内角均小于
,费马点是三角形内部对三边张角均为
的点;如果三角形有一个内角大于或等于
,费马点就是该内角所在的顶点.
已知△ABC中,角A,B,C所对的边分别为a,b,c,O为费马点.
(1)若
,
,
,求
的值;
(2)若
,
,求
的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
已知△ABC中,角A,B,C所对的边分别为a,b,c,O为费马点.
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/783d6adfa8fb1352679c5185258d842a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a3c442579603164f3fc19458677d307.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcb5bac75f36bb1dc5c8190d4dbe681d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/569b5df7e2e4642091364efefe8dddf9.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa1466856bf2570685d3629c1f813748.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c2bd0a04afc05de0f6a86ada42411f2.png)
更新时间:2024-05-11 17:28:16
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相似题推荐
解答题-问答题
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解题方法
【推荐1】在
中,内角
的对边分别为
,已知
.
(1)求角
;
(2)已知
是边
上的两个动点(
不重合),记
.
①当
时,设
的面积为
,求
的最小值;
②记
.问:是否存在实常数
和
,对于所有满足题意的
,都有
成立?若存在,求出
和
的值;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.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/c0c80cd028b9437094f864a3bc606a65.png)
(1)求角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7994ddd32e173e90d8ebc18e93496be1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6bce3d91ca23b86d8c6625f2632e437.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78f68ade9c228169668792516571e28a.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78a40d2cf43fce0c99dff3470d554eb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c495b8fd7f7bb21c177c9d50fbf6919.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
②记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ec87f241ad67ce8b51b497766886ed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4e288596fa3811dd2c17bded60e82e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d8044b3fa513f31f01ba1553934f942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
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【推荐2】已知△ABC的内角A,B,C的对边分别为a,b,c.
(1)若
的面积
,求a+c值;
(2)若2cosC(
+
)=c2,求角C.
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89a4a451aa971014953b4f7c9182a1fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67df3e5b703b2b98bec541a03252f413.png)
(2)若2cosC(
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36474f8c2ac4d65cbe4b2ed714776ac7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbf3be1d9594c75573477fcc015d4c83.png)
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【推荐3】如图,水平放置的正四棱柱形玻璃容器Ⅰ和正四棱台形玻璃容器Ⅱ的高均为32cm,容器Ⅰ的底面对角线AC的长为10
cm,容器Ⅱ的两底面对角线EG,E1G1的长分别为14cm和62cm. 分别在容器Ⅰ和容器Ⅱ中注入水,水深均为12cm. 现有一根玻璃棒l,其长度为40cm.(容器厚度、玻璃棒粗细均忽略不计)
(1)将l放在容器Ⅰ中,l的一端置于点A处,另一端置于侧棱CC1上,求l没入水中部分的长度;
(2)将l放在容器Ⅱ中,l的一端置于点E处,另一端置于侧棱GG1上,求l没入水中部分的长度.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/619096595112f0340a43b756e114dd3d.png)
(1)将l放在容器Ⅰ中,l的一端置于点A处,另一端置于侧棱CC1上,求l没入水中部分的长度;
(2)将l放在容器Ⅱ中,l的一端置于点E处,另一端置于侧棱GG1上,求l没入水中部分的长度.
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【推荐1】海宁一中高一生劳课上,朱老师组织学生在寝室楼下的荒地上种菜.如图,在一条直路边上有相距
米的A、B两定点,路的一侧是荒地,朱老师用三块长度均为10米的篱笆(不能弯折),将荒地围成一块四边形地块
(直路不需要围),经开垦后计划在三角形地块
和三角形地块
分别种植青菜、萝卜两种作物.已知两种作物的收益都与各自地块的面积的平方成正比,且比例系数均为
,即收益
,设
.
时,若要用一块篱笆将上述两三角形地块隔开,朱老师准备了15米的篱笆. 请问是否够用,并说明理由.
(2)求使两块地的总收益最大时,角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84e4123975f257306440158659634c4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5a1c3fc74e44d9ff9afc7d81bd3310e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a978e57e8d08ca663f9ee2ca41184b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97cf714ffb3fd5917a76b191640b55fe.png)
(2)求使两块地的总收益最大时,角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
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【推荐2】在
ABC中,角A,B,C所对的边分别为a,b,c,且asinAcosC+csinAcosA=
c.
(1)若c=1,sinC=
,求
ABC的面积S;
(2)若D是AC的中点,且cosB=
,BD=
,求
ABC的三边长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
(1)若c=1,sinC=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
(2)若D是AC的中点,且cosB=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9868f77d5ab5073b6145f1c6d272122e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6df397b5075ae27f938b780936fd718c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
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【推荐1】如图,在平面凸四边形
中(凸四边形指没有角度数大于
的四边形),
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/5ba246b4-b337-45fa-8b7d-4f10eb1291ad.png?resizew=138)
(1)若
,
,求
;
(2)已知
,记四边形
的面积为
.
① 求
的最大值;
② 若对于常数
,不等式
恒成立,求实数
的取值范围.(直接写结果,不需要过程)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54e7a123c9cc0e058db28841fb0edcf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9945b0e5209ab6c28f41f250677232.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/5ba246b4-b337-45fa-8b7d-4f10eb1291ad.png?resizew=138)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3017eab127d74cc39231666597485ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cda7bc571e4494fd3f8e107368c0641.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0d5a2cd05e4476fc72271e8fdb59a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
① 求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
② 若对于常数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cfa55e6a74f283827c00df59c05e1a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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【推荐2】已知a,b,c分别为
三个内角A,B,C的对边,
.
(1)若
,求角C;
(2)在(1)的条件下,设点D满足
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97020c28de4fe0cc46440d8704578c9a.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91834c1078daa51d7b4816218a6dc818.png)
(2)在(1)的条件下,设点D满足
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9941d6dacd8ccf0742471c9bda65eca5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/606ff826406d9fc8403d365762cd9e4c.png)
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