viewimage.php?id=3db5c935ecd139aa7dbcdfb018d221&no=24b0d769e1d32ca73dec84fa11d0283195504478ca9b7677dc322d30cb349b45f54005a8dcc86b106a098ff057b8eeaf8c5e5768e7b1907ce3f07632fcca4a1389e897ffbb155b73d72a09

해설지에는 반지름이 두배이면 주기도 두배라는데 2루트2배 아님..?