Question

Помогите решить .............................

Answer 1

$6)Sin(frac{35pi }{2}-alpha)+Cos(68pi -alpha)= Sin(16pi+(frac{3pi }{2}-alpha))+Cosalpha=Sin(frac{3pi }{2}-alpha)+Cosalpha=-Cosalpha+Cosalpha=0\\7)tg(9pi-alpha)+Ctg(frac{57pi }{2}+alpha)=tg(-alpha)-Ctg(28pi+(frac{pi }{2}+alpha))=-tgalpha+Ctg(frac{pi }{2}+alpha)=-tgalpha-tgalpha=-2tgalpha$

$8)frac{tg(frac{11pi }{2}+alpha)*Cos(frac{7pi }{2}-alpha)*Cos(alpha-4pi)}{Ctg(5pi-alpha)*Sin(frac{11pi}{2}+alpha)}= frac{Cos(3pi+(frac{pi }{2}-alpha)*Cosalpha }{Ctg(-alpha )*Cos(6pi-(frac{pi }{2}-alpha))}=frac{Cos(frac{pi }{2}-alpha)*Cosalpha}{-Ctgalpha*Cos(frac{pi }{2}-alpha)} =-frac{Cosalpha*Sinalpha}{Cosalpha}=-Sinalpha$

$9)Sin(7pi -alpha )*Cos(frac{15pi }{2}+beta)-Sin(frac{19pi }{2}-alpha)*Cos(6pi-beta)=Sin(6pi+(pi-alpha))*Cos(8pi-(frac{pi }{2}-beta))-Sin(10pi-(frac{pi }{2}+alpha))*Cosbeta=Sin(pi-alpha)*Cos(frac{pi }{2}-beta)+Sin(frac{pi }{2}+alpha)*Cosbeta=Sinalpha *Sinbeta+Cosalpha Cosbeta=Cos(alpha-beta)$