在中.内角对边的边长分别是.已知.. (Ⅰ)若的面积等于.求, (Ⅱ)若.求的面积.

发布时间:2021-02-20 01:28:14

(本小题满分12分)

在中,内角对边的边长分别是,已知,.

(Ⅰ)若的面积等于,求

(Ⅱ)若,求的面积.


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答案:

(Ⅰ),,(Ⅱ)


解析:

(Ⅰ)由余弦定理及已知条件得,,

又因为的面积等于,所以,得.······················ 4分

联立方程组解得,.··········································· 6分

(Ⅱ)由题意得,

即,··································································· 8分

当时,,,,,

当时,得,由正弦定理得,

联立方程组解得,.

所以的面积.·················· 12分

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