若tanα=-1,且cosα=√2/2,则角α=__ A.α=-π/4+kπ,k∈Z B.α=π/4+2kπ,k∈Z C.α=7π/4+2kπ,k∈Z D.α=3π/4+kπ,k∈Z. 请选择正确的答案,并给出正确的解题过程.

若tanα=-1,且cosα=√2/2,则角α=__ A.α=-π/4+kπ,k∈Z B.α=π/4+2kπ,k∈Z C.α=7π/4+2kπ,k∈Z D.α=3π/4+kπ,k∈Z. 请选择正确的答案,并给出正确的解题过程.

答案为C，-π/4，即7π/4满足条件，故α=7π/4+2kπ,k∈Z