2tg^2 60градусов - cth^2 30градусов - sin30cos30

[tex] { \cot }^{2} (30) = { \tan }^{2} (60) \\ 2 { \tan }^{2} (60) - { \tan}^{2} (60) - \sin(30) \cos(30) = { \tan }^{2} (60) - \sin(30) \cos(30) = { \sqrt{3} }^{2} - \frac{1}{2} \sin(60) = 3 - \frac{1}{2} \times \frac{ \sqrt{3} }{2} = 3 - \frac{ \sqrt{3} }{4} = \frac{12 - \sqrt{3} }{4} [/tex]