Question

Se cos x= 1/5, qual é o valor de cos (pi-x)
A) 5 B) 1/5+X C) -1/5 D)1/5 E)1/5-X

Answer 1

Cos(π-x)= cosπ.cosx+senπ.senx

Obs: cos.π= -1 sen.π= 0

=cosπ.cosx+senπ.senx

=-1.(1/5)+0.senx

=-1/5

Alternativa c.

:D