若cosα=a,sinβ=b(b≠1),α∈(0,),β∈(0,π),则cos(α+β)的值的个数是…（ �

若cosα=a,sinβ=b(b≠1),α∈(0,),β∈(0,π),则cos(α+β)的值的个数是…（）

A.1 B.2 C.3 D.4

答案

解析:因β∈(0,π),

故cosβ=±.

又b≠1,所以cosβ有两个值.

所以cos(α+β)也有两个值.

答案

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