sin^2+cos^2=1
cos^2=1-(√2/3)^2
cos^2=1-(2/9)
cos^2=7/9
cos=√7/3
tg=sin/cos
tg=√2/3/√7/3
tg=√(2/7)
ctg=1/tg=√(7/2)
sin^2+cos^2=1
cos^2=1-(√2/3)^2
cos^2=1-(2/9)
cos^2=7/9
cos=√7/3
tg=sin/cos
tg=√2/3/√7/3
tg=√(2/7)
ctg=1/tg=√(7/2)