Друзья, прошу помочь с 2-мя номерами по тригонометрии =)

1 [sin(2π+π/4)-cos(3π-π/4)]*[-sin(4π-π/2)]:cos(9π+π/3)= =(sinπ/4+cosπ/4)*sinπ/2:(-cosπ/3)=(√2/2+√2/2)*1:(-1/2)= =√2*(-2)=-2√2 2 [latex] \sqrt{(1-cosa)/(1+cosa)} =tg(a/2)[/latex] [latex] \sqrt{(1+cosa)/(1-cosa)} =ctg(a/2)[/latex] tg(a/2)+ctg(a/2)=sin(a/2)/cos(a/2)+cos(a/2)/sin(a/2)= =(sin²(a/2)+cos²(a/2))/(cos(a/2)sin(a/2)=2/sina sina=-4/5  2:(-4/5)=-2,5