Question

Упростить выражение :
1)$frac{sinalpha sin beta -cos( alpha - beta )}{ctg alpha }$
2)cos2x=1

Answer 1

$displaystyle frac{sin alpha sin beta -cos( alpha - beta )}{ctg alpha } = frac{sin alpha sin beta -cos alpha cos beta -sin alpha sin beta }{ctg alpha } =\\\=- frac{cos alpha cos beta }{ctg alpha } =-sin alpha cos beta$


$cos2x=1\ 2x=2 pi n,n in mathbb{Z}\ x=pi n,n in mathbb{Z}$

Answer 2

this site gonna kill me today :/ connections very very worst what's going on ? do you know anything?