Lista de exercícios do ensino médio para impressão
Resolver as equações:
a)
$\,cos\,x\,=\,cos\,\dfrac{\,\pi\,}{5}\,$
b)
$\,sec\,x\,=\,sec\,\dfrac{\,2\pi\,}{3}\,$
c)
$\,cos\,x\,=\,0\,$
d)
$\,cos\,x\,=\,1\,$
e)
$\,cos\,x\,=\,-1\,$
f)
$\,cos\,x\,=\,\dfrac{\,1\,}{2}\,$
g)
$\,cos\,x\,=\,\dfrac{\,\sqrt{\,2\,}\,}{2}\,$
h)
$\,cos\,x\,=\,\dfrac{\,\sqrt{\,3\,}\,}{2}\,$

resposta: a) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pm\,\frac{\pi}{5}\,+\,2k\pi \, \rbrace\,$
b) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pm\,\frac{2\pi}{3}\,+\,2k\pi \, \rbrace\,$
c) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pm\,\frac{\pi}{2}\,+\,2k\pi \, \rbrace\, =\,$ $\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\frac{\pi}{2}\,+\,k\pi \, \rbrace\,$
d) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,2k\pi \, \rbrace\,$
e) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pi\,+\,2k\pi \, \rbrace\,$
f) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pm\,\frac{\pi}{3}\,+\,2k\pi \, \rbrace\,$
g) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pm\,\frac{\pi}{4}\,+\,2k\pi \, \rbrace\,$
h) $\,S\,=\,\lbrace\,x\,\in\,{\rm\,I\!R}\;|\;\,x\,=\,\pm\,\frac{5\pi}{6}\,+\,2k\pi \, \rbrace\,$

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Veja exercÍcio sobre:
trigonometria
equações trigonométricas