sin^n(x)를 부분적분을 사용해서 적분하는 과정을 적어야 하는데 도저히 모르겠어요 ㅠ.ㅠ
왈리스 공식인가 하는것도 있는 모양이던데 그건 아직 안배운거라서 사용안하고 풀어야 할것 같거든요..
점화식 비스무리한게 나올듯 하면서도 안나오네요 ㅠ.ㅠ 
돠주시면 정말 감사하겠습니당 ㅋ