Given the definite integral $\displaystyle \int_{\sqrt{2}}^{2} \frac{f(x)}{2\pi}dx$, which of the following integrals are equivalent and justify your answer. (There could be more then one.)

A. $\displaystyle \int_{0}^{2\pi} f(\frac{x}{\pi})dx$

B. $\displaystyle \int_{\frac{1}{4}}^{\frac{1}{2}}f(2sin(x\pi))cos(x \pi)dx$

C. $\displaystyle -\frac{1}{2\pi}\int_{1}^{2}\frac{f(\frac{1}{x})}{x^ 2}dx$

I need some help on this one...