ĐKXĐ: \(2x-\dfrac{\Omega}{2}\ne\dfrac{\Omega}{2}+k\Omega\)
=>\(2x\ne\Omega+k\Omega\)
=>\(x\ne\dfrac{\Omega}{2}+\dfrac{k\Omega}{2}\)
Vậy: TXĐ: \(D=R\backslash\left\{\dfrac{\Omega}{2}+\dfrac{k\Omega}{2}\right\}\)
ĐKXĐ: \(cos\left(2x-\dfrac{\pi}{2}\right)\ne0\)
\(\Rightarrow2x-\dfrac{\pi}{2}\ne\dfrac{\pi}{2}+k\pi\)
\(\Rightarrow2x\ne k\pi\)
\(\Rightarrow x\ne\dfrac{k\pi}{2}\)