English: So a_(n) and b_(n) can be calculated as, $a_{n} = \frac{1}{\pi}xcos\ nx\ dx = \frac{1}{\pi n}\left\lbrack \frac{\cos\ n\pi\ - 1}{n} \right\rbrack = \{\ \ \ \ \ \ \ \ 0\ \ \ \ \ ,\ \ \ \ when\ n\ is\ even\ - \frac{2}{\pi n^{2}}\ \ ,\ \ \ \ when\ n\ is\ odd$ So, depending upon even or odd, the value of cos  nπ  changes.
Telugu: కాబట్టి a_(n) మరియు b_(n) లను ఇలా లెక్కించవచ్చు, $a_{n} = \frac{1}{\pi}xcos\ nx\ dx = \frac {2}{2}{1}{\pi n}\లెఫ్ట్\lbrack \frac{\cos\pi\ - 1}{n} \కుడి\rbrack = \\\ \ \n\ \ \n\ \\n\ \\ \ \ \ \