\(\int {\sin x} .\cos xdx\) bằng:

A. \(\frac{{c{\rm{os2}}x}}{4} + C\)

B. \( - \frac{{{{\sin }^2}x}}{2} + C\)

C. \(\frac{{{{\sin }^2}x}}{2} + C\)

D. \(\frac{{c{\rm{o}}{{\rm{s}}^2}x}}{2} + C\)