TXĐ: \(sinx-cosx>=0\)
=>\(\sqrt{2}\cdot cos\left(x-\dfrac{\Omega}{4}\right)>=0\)
=>\(cos\left(x-\dfrac{\Omega}{4}\right)>=0\)
=>\(\dfrac{3}{2}\Omega+k2\Omega< =x-\dfrac{\Omega}{4}< =\dfrac{5}{2}\Omega+k2\Omega\)
=>\(\dfrac{7}{4}\Omega+k2\Omega< =x< =\dfrac{11}{4}\Omega+k2\Omega\)