解由角α的终边是射线Y=-x(x>0)
则a的终边在第四象限
故a=2kπ-π/4,k属于Z.
故sina=sin(2kπ-π/4)=sin(-π/4)=-√2/2
cosa=cos(2kπ-π/4)=cos(-π/4)=√2/2
tana=tan(2kπ-π/4)=tan(-π/4)=-tanπ/4=-1
解由角α的终边是射线Y=-x(x>0)
则a的终边在第四象限
故a=2kπ-π/4,k属于Z.
故sina=sin(2kπ-π/4)=sin(-π/4)=-√2/2
cosa=cos(2kπ-π/4)=cos(-π/4)=√2/2
tana=tan(2kπ-π/4)=tan(-π/4)=-tanπ/4=-1