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[잡담] 갑자기 궁금해져서 질문이요

뉴＿턴 2019.07.27 00:46 조회 329

페이스북 트위터 카카오톡 카카오스토리 네이버블로그 네이버밴드

반지름이 r인 원의 넓이 리만 적분으로 구할 수 있을까요??

$( \iint_{-r}^{r}x^2+y^2=r^2 )$ 을 하면 될 것 같기도 한데 이중적분을 못해서,,,,,, 아시는 분은 이중이상의 적분을 하면 설명도 같이 부탁드리고, 삼각함수를 써도 설명 부탁드릴게요^^

다음글 제가 피타고라스 정리의 새로운 증명 방법을 찾아낸 것 같습니다.

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극좌표계에서 하시면 삼각형 여러개 더하는 거니까

높이 r, 밑변 $r d\theta$ 라고 하면 $\int_0^{2\pi}\frac{1}{2}r\cdot rd\theta$

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