Question

Найдите cos при известном sin и tg

Answer 1

$\displaystyle\bf\\Sin\alpha =0,8 \ \ \ ; \ \ \ tg\alpha =\frac{4}{3} \\\\\\tg\alpha =\frac{Sin\alpha }{Cos\alpha } \\\\\\Cos\alpha =\frac{Sin\alpha }{tg\alpha } =0,8:\frac{4}{3} =\frac{4}{5} \cdot\frac{3}{4} =\frac{3}{5} =0,6\\\\\\Otvet \ : \ Cos\alpha =0,6$