Question

ctgA = 3/4 16. Найдите соs A​

Answer 1

Решение:

$ctg~A = \dfrac{3}{4} ;$

$tg~A = \dfrac{1}{ctg~A} = \dfrac{4}{3} ;$

$cos^2A = \dfrac{1}{1 + tg^2A} =\dfrac{1}{1 + \dfrac{16}{9} } = \dfrac{9}{25} ;$

$\boxed{cos~A = \dfrac{3}{5} .}$