Question

помогите пожалуйста срочно

Answer 1

$1 + ( \sqrt{3} ) {}^{2} - ( \frac{1}{2} ) {}^{2} - ( \frac{ \sqrt{3} }{2} ) {}^{2} = 1 + 3 - 0.25 - 0.75 = 3$

$tg1.9 \times ctg1.9 = 1$

$ctg {}^{2} ( - \frac{5\pi}{6} ) = ctg {}^{2} \frac{\pi}{6} = (\sqrt{3} ) {}^{2} = 3$