Question

ctg(-420°)+cos810°-sin(-2,25П)

Answer 1

ctg(-360-60)+cos(720+90)-sin(-2π-π/4)=-ctg60+cos90+sinπ/4=-1/√3+0+√2/2=
=(3√2-2√3)/6

Answer 2

$ctg(-420)+cos810-sin(-2,25pi)=ctg(-60)+cos90-sin(-frac{pi}{4})=\=-frac{sqrt3}{3}+0+frac{sqrt{2}}{2}=frac{3sqrt2-2sqrt3}{6}=frac{sqrt6(sqrt3-sqrt2)}{6}=frac{sqrt3-sqrt2}{sqrt6}$