Question

23.9. Найдите знак значения выражения: 1) sin135º. cos210° .tg405° • ctg330° • cos560°;
2) sin425º. cos250°. ctg420° . tg330° • sin 750°;
131 71
3) sin
7
ctg
3.
51
21
COS
3
77
COS
6
9π
tg
4
111
tg
4
6
81
• COS
4 ;
111
sin
6
.
ctg
4) sin
3
3

Answer 1

$sin425^\circ \cdot cos250^\circ \cdot ctg420^\circ \cdot tg330^\circ =\\\\=sin(360^\circ +65^\circ )\cdot cos(180^\circ +70^\circ )\cdot ctg(360^\circ +60^\circ )\cdot tg(270^\circ +60^\circ )=\\\\=\underbrace {sin65^\circ }_{0}\cdot (\underbrace {-cos70^\circ }_{0}\cdot (\underbrace {-ctg60^\circ }_{0$