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수학동아 - 폴리매스
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함께 풀고 싶은 문제
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[창의 퍼즐] [기하]미끄럼틀 아닌 미끄럼틀
△π 2020.06.06 21:58 조회 673

 

(로고는 지나가던 사람님께서 만들어 주셨습니다!)

모선이 120cm, 밑면의 반지름이 40cm인 원뿔 모양의 구조물이 있다. 이때, 밑면의 원 가장자리에 있는 점 B와, 그 20cm 위에 있는 점 A가 있다. 이들 사이에 원뿔을 한 바퀴 돌아서 미끄럼틀을 만드려고 한다. 미끄럼틀을 최단경로로 제작하기로 했다. (단, 모선을 따라 A에서 B로 바로 가는 경우는 제외하고, 무조건 원뿔을 한 바퀴 돌아야 한다.) 그런데, 문제가 생겼다. '미끄럼틀'인데, 오르막 구간이 생긴 것이다!! 이 오르막 구간의 길이는 얼마일까?

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