Question

Tg20cos50+cos40 значение

Answer 1

$tg20^0cos50^0+cos40^0=$
$tg a=\frac{sin a}{cos a}$
$sin a=cos(90-a)$
-------------------------------
$\frac{sin20^0sin40^0}{cos20^0}+cos40^0=$
сводим в одну дробь
$\frac{sin20^0sin40^0+cos40^0cos20^0}{cos20^0}=$
$cos(a-b)=cos a cos b + sin a sin b$
-----------------
$\frac{cos(40^0-20^0)}{cos 20^0}=\frac{cos 20^0}{cos 20^0}=1$
ответ: 1