Question

Qual é o valor da expressão cos2pi/3 + sen3pi/2 + tg 5pi/4?

ajudem :(

Answer 1

$\text{cos}\left(\dfrac{2\pi}{3}\right)=\text{cos}(120^{\circ})=-\text{cos}(60^{\circ})=-\dfrac{1}{2}$

$\text{sen}\left(\dfrac{3\pi}{2}\right)=\text{sen}(270^{\circ})=-\text{sen}(90^{\circ})=-1$

$\text{tg}\left(\dfrac{5\pi}{4}\right)=\text{tg}(45^{\circ})=1$

Logo

$\text{cos}\left(\dfrac{2\pi}{3}\right)+\text{sen}\left(\dfrac{3\pi}{2}\right)+\text{tg}\left(\dfrac{5\pi}{4}\right)=-\dfrac{1}{2}-1+1=\boxed{-\dfrac{1}{2}}$