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Question Number 30507 by abdo imad last updated on 22/Feb/18

f i n d \int_{- π}^{π} \frac{d x}{2 + c o s x}

2) i f \frac{1}{2 + c o s x} = \frac{a_{0}}{2} + \sum_{n ⩾ 1} a_{n} c o s (n x) f i n d a_{0} a n d a_{n} .