sin a = 0.8 

sin= y/R

cos=x/R

tan=x/y

cotan=y/x

R=1

y=0.8 = sin a

По пифагору

x=-sqrt(1-0.8^2)=-0.6 = cos а

tan(a)=sin(a)/cos(a)=0.8/0.6=-1-1/3

cotan(a)=cos(a)/sin(a)=-0.75