Question

O valor da expressão cos (2π/3) + sen (3π/2) é:

-3/2

-1/2

1/2

3/2

-1

Answer 1

$\texttt{Olhar para baixo}$

$\cos( \cfrac{2\pi}{3} ) + \sin( \cfrac{3\pi}{2} ) \\ \\ \sin( \frac{\pi}{2} - \dfrac{2\pi}{3} ) + \sin( \dfrac{3\pi}{2} ) \\ \\ \sin( - \dfrac{\pi}{6} ) + \sin( \dfrac{3\pi}{2} ) \\ \\ - \sin( \dfrac{\pi}{6} ) + \sin( \frac{ 3\pi}{2} ) \\ \\ - \dfrac{1}{2} -1 \\ \\ \boxed{ - \dfrac{ 3}{2} }\checkmark$