1)ctga=8
sin²a=1:(1+ctg²a)=1:(1+64)=1/65⇒sina=1/√65
cosa=√(1-sin²a)=√(1-1/65)=8/√65
(sin(13π/2-a)-ctg(5π+a))/(1+sin(2π-a))=(cosa-ctga)/(1-sina)=(8/√65 -8)/(1-1/√65)=
=(8-8√65)/(√65-1)=-8(√65-1)/(√65-1)=-8
2)(cosacosb+sinasinb-2cosacosb)/(2cosasinb+sinacosb-cosasinb)*2√3=
=(sinacosb-cosacosb)/(cosasinb+sinacosb) *2√3=-cos(a+b)/sin(a+b)*2√3=
=-cos120/sin120*2√3=-ctg120*2√3=ctg60*2√3=1/√3*2√3=2