设三角形ABC所对的边分别为a.b.c.且a×cosc+½c=b (1)求角A的大小 (2)求cos设三角形ABC所对的边分别为a.b.c.且a×cosc+½c=b(1)求角A的大小(2)求cosB+cosC的取值范围
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![设三角形ABC所对的边分别为a.b.c.且a×cosc+½c=b (1)求角A的大小 (2)求cos设三角形ABC所对的边分别为a.b.c.且a×cosc+½c=b(1)求角A的大小(2)求cosB+cosC的取值范围](/uploads/image/z/5469922-10-2.jpg?t=%E8%AE%BE%E4%B8%89%E8%A7%92%E5%BD%A2ABC%E6%89%80%E5%AF%B9%E7%9A%84%E8%BE%B9%E5%88%86%E5%88%AB%E4%B8%BAa.b.c.%E4%B8%94a%C3%97cosc%EF%BC%8B%26%23189%3Bc%EF%BC%9Db+%EF%BC%881%EF%BC%89%E6%B1%82%E8%A7%92A%E7%9A%84%E5%A4%A7%E5%B0%8F+%EF%BC%882%EF%BC%89%E6%B1%82cos%E8%AE%BE%E4%B8%89%E8%A7%92%E5%BD%A2ABC%E6%89%80%E5%AF%B9%E7%9A%84%E8%BE%B9%E5%88%86%E5%88%AB%E4%B8%BAa.b.c.%E4%B8%94a%C3%97cosc%EF%BC%8B%26%23189%3Bc%EF%BC%9Db%EF%BC%881%EF%BC%89%E6%B1%82%E8%A7%92A%E7%9A%84%E5%A4%A7%E5%B0%8F%EF%BC%882%EF%BC%89%E6%B1%82cosB%EF%BC%8BcosC%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4)
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