Question

Resolva a expressão:

y = (sen 30° + sen 210°) + sen 330°

( ) 1/2
( ) -1/2
( ) 0
( ) -1

Answer 1

$\displaystyle \text{y} = \text{sen}(30^\circ)+\text{sen}(210^\circ)+\text{sen}(330^\circ)$

Sabemos que :

$\displaystyle \text{sen}(30^\circ) = \frac{1}{2}$

$\displaystyle \text{sen}(210^\circ) \to \text{sen}(180^\circ+30^\circ) = -\text{sen}(30^\circ) = \frac{-1}{2}$  

$\displaystyle \text{sen}(330^\circ) \to \text{sen}(360^\circ-30^\circ) = -\text{sen}(30^\circ) = \frac{-1}{2}$

Substituindo :  

$\displaystyle \text{y} = \text{sen}(30^\circ)+\text{sen}(210^\circ)+\text{sen}(330^\circ)$

$\displaystyle \text{y} = \frac{1}{2}+\frac{-1}{2}+\frac{-1}{2}$

$\huge\boxed{\displaystyle \text{y} = \frac{-1}{2}}\checkmark$

Answer 2

Resposta:

-1/2

Espero ter ajudado