化简【sin(nπ+α)cos(nπ-阿α)】/{cos【(n+1)π-α】}

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化简【sin(nπ+α)cos(nπ-阿α)】/{cos【(n+1)π-α】}化简【sin(nπ+α)cos(nπ-阿α)】/{cos【(n+1)π-α】}化简【sin(nπ+α)cos(nπ-阿α)

化简【sin(nπ+α)cos(nπ-阿α)】/{cos【(n+1)π-α】}
化简【sin(nπ+α)cos(nπ-阿α)】/{cos【(n+1)π-α】}

化简【sin(nπ+α)cos(nπ-阿α)】/{cos【(n+1)π-α】}
n为偶数时,原式=sinαcosα/(-cosα)=-sinα
n为奇数时,原始=(-sinα)(-cosα)/cosα=sinα