Sin -810° + cos 900° - ctg 675°

Question

Sin -810° + cos 900° - ctg 675°

Answer 1

=-sin 810°+cos 900°-ctg 675°=-sin(2π+90°)+cos(2π+180°)-ctg(2π-45⁰)=-sin 90°+cos 180°-(-ctg 45°)=-1-1+1=-1