a) sin300° = sin(360° - 60°) = -sin60° = -$$\frac{\sqrt{3}}{2}$$.
б) tg$$\frac{2π}{3}$$ = tg(120°) = tg(180° - 60°) = -tg60° = -$$\sqrt{3}$$.
в) 2sin$$\frac{π}{2}$$ - cos$$\frac{3π}{2}$$ = 2sin90° - cos270° = 2 * 1 - 0 = 2.
Ответ:
a) -$$\frac{\sqrt{3}}{2}$$; б) -$$\sqrt{3}$$; в) 2.