Nghiệm của phương trình $\sin x =  - 1$ là:

$x = \dfrac{\pi }{2} + k2\pi$.

$x = \dfrac{k\pi }{2}$.

$x = k2\pi$.

$x = \dfrac{\pi }{6} + k2\pi$.

$y = \sin x$

$y = \cos x$

$y = \sin 2x$  

$y = \cot x$ 

$\dfrac{{2\pi }}{3}$

$\dfrac{\pi }{3}$

$\dfrac{{4\pi }}{3}$

$\dfrac{{7\pi }}{3}$

$\max y = 4;\min y = \dfrac{3}{4}$

$\max y = 3;\min y = 2$

$\max y = 4;\min y = 2$

$\max y = 3,\min y = \dfrac{3}{4}$

$\left( {\dfrac{\pi }{2} + k2\pi ;\dfrac{{3\pi }}{2} + k2\pi } \right)$

$\left( { - \pi  + k2\pi ;k2\pi } \right)$

$\left( {k2\pi ;\pi  + k2\pi } \right)$                           

$R$

$y = {x^2} - \sin x$

$y = {x^2} + \sin x$

$y = {x^3} - \sin x$

$y = \cos x - {x^2}$