Question

Срочно помогите пожалуйста даю 28 баллов​

Answer 1

Ответ:

$1)\ \ sin225^\circ \, cos120^\circ \, tg330^\circ \, ctg240^\circ =\\\\=sin(180^\circ +45^\circ )\, cos(180^\circ -60^\circ )\, tg(360^\circ -30^\circ )\, ctg(180^\circ +60^\circ)=\\\\=-sin45^\circ \, (-cos60^\circ )\, (-tg30^\circ )\, ctg60^\circ =-\dfrac{\sqrt2}{2}\cdot \dfrac{1}{2}\cdot \dfrac{\sqrt3}{3}\cdot \dfrac{\sqrt3}{3}=-\dfrac{\sqrt2}{12}$

$2)\ \ sin\Big(-\dfrac{13\pi }{6}\Big)-cos\dfrac{11\pi }{2}+tg\dfrac{4\pi}{5}\cdot ctg\dfrac{6\pi }{5}=\\\\\\=-sin\Big(2\pi +\dfrac{\pi}{6}\Big)-cos\Big(4\pi +\pi +\dfrac{\pi}{2}\Big)+tg\Big(\pi -\dfrac{\pi}{5}\Big)\cdot ctg\Big(\pi +\dfrac{\pi}{5}\Big)=\\\\\\=-sin\dfrac{\pi}{6}+cos\dfrac{\pi}{2}+tg\dfrac{\pi}{5}\cdot ctg\dfrac{\pi}{5}=-\dfrac{1}{2}+0+1=-\dfrac{1}{2}$