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> 已知向量 .（1）若 ,求的值；（2）记，在△ ABC中，角 A， B， C的对边分别是 a, b, c，且满足（2 a- c）cos B= bcos C，求函数 f( A)的取值范围.

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发布时间：2024-09-13

已知向量 .（1）若 ,求的值；（2）记，在△ ABC中，角 A， B， C的对边分别是 a, b, c，且满足（2 a- c）cos B= bcos C，求函数 f( A)的取值范围.

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已知向量 .（1）若 ,求 的值；（2）记 ，在△ ABC中，角 A， B， C的对边分别是 a, b, c，且满足（2 a- c）cos B= bcos C，求函数 f( A)的取值范围.

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已知向量 .（1）若 ,求的值；（2）记，在△ ABC中，角 A， B， C的对边分别是 a, b, c，且满足（2 a- c）cos B= bcos C，求函数 f( A)的取值范围.