题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-51919.png)
(1)当p=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-61154.png)
(2)若角B为锐角,求p的取值范围.
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-21542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-21542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-66215.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030746-27908.png)
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030746-77498.png)
故可知a,c为方程x2﹣
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030746-43297.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-21542.png)
进而求得a=1,c=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-21542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-21542.png)
(2)解:由余弦定理得b2=a2+c2﹣2accosB=(a+c)2﹣2ac﹣2accosB=p2b2﹣
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030746-54892.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030746-90922.png)
即p2=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030747-13154.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030747-90908.png)
因为0<cosB<1,
所以p2∈(
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030747-13154.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-66215.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030747-48248.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030747-48248.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-66215.png)
又由sinA+sinC=psinB知,p是正数
故
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030745-66215.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030746-27908.png)
核心考点
试题【(2011•浙江)在△ABC中,角A,B,C,所对的边分别为a,b,c.已知sinA+sinC=psinB(p∈R).且ac=b2.(1)当p=,b=1时,求a】;主要考察你对解三角形应用等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030741-54476.png)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030742-34330.png)
(2)若cosB=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030742-94498.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030735-36095.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030736-91883.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030736-62022.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030736-38833.png)
A.![]() | B.![]() | C.![]() ![]() | D.![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030719-86225.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-94638.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030719-86225.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-94638.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-29086.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-88168.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-81808.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-97852.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-81808.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-29086.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-84966.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-81808.png)
(1)某移动公司将在
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-29086.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-19633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-19633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-19633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-57527.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030719-86225.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-19633.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-50349.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-94638.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030721-19633.png)
(2)环保部门将在
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-29086.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030722-93488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030722-69497.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030722-93488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030719-86225.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030720-94638.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030722-93488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030722-13640.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030711-10886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030711-66253.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030711-41689.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030711-17212.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030712-40533.png)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030712-37529.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030711-10886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020030712-96577.png)
A.a、c、b 成等比数列 B.a、c、b 成等差数列
C.a、b、c 成等差数列 D.a、b、c成等比数列
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