已知f(α)=【sin(π-α)*cos(2π-α)]/cos(-π-α)*tan(α+π),求f(-31π/3)的值
问题描述:
已知f(α)=【sin(π-α)*cos(2π-α)]/cos(-π-α)*tan(α+π),求f(-31π/3)的值
答
f(α)=【sin(π-α)*cos(2π-α)]/cos(-π-α)*tan(α+π =sinαcosα/(-cosα)(-tanα) =sinαcosα/sinα =cosαf(-31π/3)=cos(-31π/3)=cos(-10π-π/3)=cosπ/3=1/2龙...