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Today's calculation of Integral 296

Source: 2008 Ritsumeikan University entrance exam

February 10, 2008
calculusintegrationtrigonometrycalculus computations

Problem Statement

Let a_n\equal{}\int_0^{\frac{\pi}{2} } (1\minus{}\sin t)^n\sin 2t\ dt. (1) Find \sum_{n\equal{}1}^{\infty} a_n. (2) Find \sum_{n\equal{}1}^{\infty} \frac{a_n}{n}. (3) Find \sum_{n\equal{}1}^{\infty} (n\plus{}1)(a_n\minus{}a_{n\plus{}1}).