Can anyone help me in this. There's some kind of trick that

>what is trigonometry
http://www.wolframalpha.com/input/?i=sin%28x%29*cos%28y%29

Back2School with you

>>7810298
That isn't the problem. Computing 10-point dft is time consuming. There's somekind of trick in here

DFT is a linear function, so I would write
[math] \displaystyle \cos \left ( \frac{3 \pi }{5}n \right ) \sin \left ( \frac{4 \pi }{5}n \right )= \frac{1}{2} \left ( \sin \left ( \frac{ \pi }{5}n \right )+ \sin \left ( \frac{7 \pi }{5}n \right ) \right )[/math]
and sum the 10-point DFT for the two sine functions.