Question

sin(-1920°)=?cos(-1560°）=?tan(-17π/6）=?

Answer 1

sin(-1920º)=- sin1920º=-sin(1800º+120º)=-sin120 º=-sin(180º-60º)=-sin60º=-√3/2；

cos(-1560°）= cos1560°=cos(1800º-240º)=cos240º=cos(180º+60º)=-cos60º=-1/2；

tan(-17π/6）=- tan17π/6=-tan(2π+5π/6)=-tan5π/6=-tan(π-π/6)=tanπ/6=√3/3.