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A:prefer
B:want
C:know
D:review
已知二面角α-AB-β的平面角是锐角θ,α内一点C到β的距离为3,点C到棱AB的距离为4,那么tanθ的值为( )
解方程组: {3a−b+c=72a+3b=−2a+b+c=−1