Question

Consultando o círculo trigonométrico. Indique o valor de:
a) sen 3π/2 =
b) sen 5π/2 =
c) sen 11π/2 =
d) Cos 7π/9 =
e) Cos ( - 3π/2 ) =

Answer 1

$\tt{a)}~\sf{sen\left(\dfrac{3\pi}{2}\right)=-1}\\\tt{b)}~\sf{sen\left(\dfrac{5\pi}{2}\right)=sen\left(\dfrac{\pi}{2}\right)=1}\\\tt{c)}~\sf{sen\left(\dfrac{11\pi}{2}\right)=sen\left(\dfrac{3\pi}{2}\right)=-1}\\\tt{d)}~\sf{cos\left(\dfrac{7\pi}{9}\right)=-cos\left(\dfrac{2\pi}{9}\right)\approx-0,76}\\\tt{e)}~\sf{cos\left(-\dfrac{3\pi}{2}\right)=cos\left(\dfrac{3\pi}{2}\right)=0}$

Answer 2

Oie, Td Bom?!

a) sen(3π/2) = - 1

b) sen(5π/2) = sen(π/2 + 2π) = sen(π/2) = 1

c) sen(11π/2) = sen(3π/2 + 2 . 2π) = sen(3π/2) = - 1

d) cos(7π/9) ≈ - 0,766044...

e) cos(- 3π/2) = cos(3π/2) = 0

Att. Makaveli1996