Question

помогите пожалуйста в и г ​

Answer 1

$\displaystyle\bf\\1)\\\\\frac{tg\dfrac{\pi }{10}+tg\dfrac{3\pi }{20} }{1-tg\dfrac{\pi }{10}\cdot tg\dfrac{3\pi }{20} } =tg\Big(\frac{\pi }{10} +\frac{3\pi }{20} \Big)=tg\frac{5\pi }{20} =tg\frac{\pi }{4} =1\\\\\\2)$

$\displaystyle\bf\\\frac{Sin\dfrac{5\pi }{18} Cos\dfrac{\pi }{9}-Sin\dfrac{\pi }{9} Cos\dfrac{5\pi }{18}}{Sin\dfrac{5\pi }{12} Sin\dfrac{7\pi }{12} -Cos\dfrac{5\pi }{12} Cos\dfrac{7\pi }{12} } =\frac{Sin\Big(\dfrac{5\pi }{18} -\dfrac{\pi }{9} \Big)}{-Cos\Big(\dfrac{5\pi }{12} +\dfrac{7\pi }{12} \Big)} =-\frac{Sin\dfrac{3\pi }{18} }{Cos\pi } =\\\\\\=-\frac{Sin\dfrac{\pi }{6} }{-1} =\frac{1}{2} =0,5$