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

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...