[m]sin^{2}\frac{\pi }{4}=(\frac{\sqrt{2}}{2})^{2}=\frac{2}{4}=\frac{1}{2}[/m]
[m]2\cdot sin^{2}\frac{\pi }{4}=2\cdot \frac{1}{2}=1[/m]
[m]ctg(-\frac{\pi }{6})=-\sqrt{3}[/m]
[m]\sqrt{3}\cdot ctg(-\frac{\pi }{6}) =\sqrt{3}\cdot(-\sqrt{3})=-1[/m]
[m]2\cdot sin^{2}\frac{\pi }{4}+\sqrt{3}\cdot ctg(-\frac{\pi }{6})=1+(-1)=0[/m]