Cho X ( e j ω ) = e − j ω 2 s i n 3 ω . Hãy xác định giá trị phần thực R e X ( e j ω )

$\text{R}\text{e}\left[X\left(e{}^{j\omega }\right)\right]=\text{s}\text{i}\text{n}3\omega \text{c}\text{o}\text{s}\frac{\omega }{2}$

$\text{R}\text{e}\left[X\left(e{}^{j\omega }\right)\right]=-\text{s}\text{i}\text{n}3\omega \text{s}\text{i}\text{n}\frac{\omega }{2}$

$\text{R}\text{e}\left[X\left(e{}^{j\omega }\right)\right]=\text{s}\text{i}\text{n}3\omega \text{s}\text{i}\text{n}\frac{\omega }{2}$

$\text{R}\text{e}\left[X\left(e{}^{j\omega }\right)\right]=-\text{s}\text{i}\text{n}3\omega \text{c}\text{o}\text{s}\frac{\omega }{2}$