[tex](sin 45^o - tg 60^o) * cos 30^o = (\frac{\sqrt{2} }{2} - \sqrt{3}) * \frac{1}{2} = (\frac{\sqrt{2} }{2} - \frac{2\sqrt{3}}{2} ) * \frac{1}{2} = \frac{\sqrt{2}-2\sqrt{3} }{4}[/tex]