18. sin(π/3) = √3/2; cos(π/3) = 1/2; tg(π/3) = √3; ctg(π/3) = 1/√3

Для угла \(\frac{\pi}{3}\): \( g x=\frac{\sin x}{\cos x}\), а \(\ctg x=\frac{\cos x}{\sin x}\).

\( g\frac{\pi}{3}=\frac{\frac{\sqrt3}{2}}{\frac12}=\sqrt3\); \(\ctg\frac{\pi}{3}=\frac{\frac12}{\frac{\sqrt3}{2}}=\frac{1}{\sqrt3}=\frac{\sqrt3}{3}.\)

Ответ: \(\sin\frac{\pi}{3}=\frac{\sqrt3}{2}\), \(\cos\frac{\pi}{3}=\frac12\), \( g\frac{\pi}{3}=\sqrt3\), \(\ctg\frac{\pi}{3}=\frac{1}{\sqrt3}\).