Question

Sabendo que cos x=4/5 e que pertence ao 4 quadrante calcule: a)sen x b)tg x c)cotg x d) sec x e)cossec x

Answer 1

a) sen² x = 1 - cos² x
sen² x = 1 - (4/5)²
sen² x = 1 - 16/25
sen x = √9/√25 = - 3/5

sen é negativo no 4Q


b) tg x = sen x/cos x
tg x = - 3/5/4/5
tg x = - 3/4


c) cotg x = 1/tg x
cotg x = - 1/3/4 = - 4/3


d) sec x = 1/cos x
sec x = 1/4/5 = 5/4


e) cossec x = 1/sen x
cossec x = - 1/3/5 = - 5/3