求证：(sin(kπ-α)cos(kπ+α))/(sin((k+1)π+α)cos((k+1)π+α))=-1,k∈Z
问题描述：
求证：(sin(kπ-α)cos(kπ+α))/(sin((k+1)π+α)cos((k+1)π+α))=-1,k∈Z
答
证明:
左边=sina*(-cosa)/[-sina*(-cosa)]=-1=右边.
得证.