2. cos(a)=0.6, sin(a)=? tg(a)=?

sin(a) = sqrt(1 - cos^2(a)) = sqrt(1 - 0.6^2) = sqrt(1 - 0.36) = sqrt(0.64) = 0.8. tg(a) = sin(a) / cos(a) = 0.8 / 0.6 = 4/3 ≈ 1.33