{"id":554,"date":"2012-12-29T23:02:57","date_gmt":"2012-12-29T14:02:57","guid":{"rendered":"http:\/\/www.roundown.net\/nyushi\/?p=554"},"modified":"2021-10-31T07:39:52","modified_gmt":"2021-10-30T22:39:52","slug":"tkb200901","status":"publish","type":"post","link":"https:\/\/www.roundown.net\/nyushi\/tkb200901\/","title":{"rendered":"\u6771\u5927\u6587\u7cfb2009\uff1a\u7b2c1\u554f"},"content":{"rendered":"
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\u5ea7\u6a19\u5e73\u9762\u306b\u304a\u3044\u3066\u539f\u70b9\u3092\u4e2d\u5fc3\u3068\u3059\u308b\u534a\u5f84 \\(2\\) \u306e\u5186\u3092 \\(C _ 1\\) \u3068\u3057, \u70b9 \\((1,0)\\) \u3092\u4e2d\u5fc3\u3068\u3059\u308b\u534a\u5f84 \\(1\\) \u306e\u5186\u3092 \\(C _ 2\\) \u3068\u3059\u308b.\r\n\u307e\u305f, \u70b9 \\((a,b)\\) \u3092\u4e2d\u5fc3\u3068\u3059\u308b\u534a\u5f84 \\(t\\) \u306e\u5186\u304c \\(C _ 3\\) \u304c, \\(C _ 1\\) \u306b\u5185\u63a5\u3057, \u304b\u3064 \\(C _ 2\\) \u306b\u5916\u63a5\u3059\u308b\u3068\u4eee\u5b9a\u3059\u308b. \u305f\u3060\u3057, \\(b\\) \u306f\u6b63\u306e\u5b9f\u6570\u3068\u3059\u308b.<\/p>\r\n

    \r\n

  1. (1)<\/strong>\u3000\\(a , b\\) \u3092 \\(t\\) \u3092\u7528\u3044\u3066\u8868\u305b. \u307e\u305f, \\(t\\) \u304c\u3068\u308a\u5f97\u308b\u5024\u306e\u7bc4\u56f2\u3092\u6c42\u3081\u3088.<\/p><\/li>\r\n

  2. (2)<\/strong>\u3000\\(t\\) \u304c (1)<\/strong> \u3067\u6c42\u3081\u305f\u7bc4\u56f2\u3092\u52d5\u304f\u3068\u304d, \\(b\\) \u306e\u6700\u5927\u5024\u3092\u6c42\u3081\u3088.<\/p><\/li>\r\n<\/ol>\r\n

    \r\n\r\n

    \u3010 \u89e3 \u7b54 \u3011<\/h2>\r\n\"tokyo_b_2009_01_01\"\r\n

    (1)<\/strong><\/p>\r\n

    \\(C _ 2 , C _ 3\\) \u306e\u4e2d\u5fc3\u3092\u305d\u308c\u305e\u308c A , B \u3068\u304a\u304f\u3068\r\n\\[\\begin{align}\r\n\\text{OB} = \\sqrt{a^2+b^2} & = 2-t \\\\\r\n\\text{\u2234} \\quad a^2+b^2 & = (2-t)^2 \\quad ... [1] , \\\\\r\n\\text{AB} = \\sqrt{(a-1)^2+b^2} & = 1+t \\\\\r\n\\text{\u2234} \\quad (a-1)^2+b^2 & = (1+t)^2 \\quad ... [2]\r\n\\end{align}\\]\r\n\\([1] -[2]\\) \u3088\u308a\r\n\\[\\begin{align}\r\n2a-1 & = 3-6t \\\\\r\n\\text{\u2234} \\quad a & = \\underline{2-3t}\r\n\\end{align}\\]\r\n[1] \u306b\u4ee3\u5165\u3057\u3066, \\(b \\gt 0\\) \u306a\u306e\u3067\r\n\\[\\begin{align}\r\nb & = \\sqrt{(2-t)^2-(2-3t)^2} \\\\\r\n& = \\underline{\\sqrt{8t(1-t)}}\r\n\\end{align}\\]\r\n\\(b\\) \u304c\u5b9f\u6570\u306a\u306e\u3067\u6839\u53f7\u5185\u306f\u6b63\u3060\u304b\u3089, \\(t\\) \u306e\u3068\u308a\u5f97\u308b\u5024\u306e\u7bc4\u56f2\u306f\r\n\\[\r\n\\underline{0 \\lt t \\lt 1}\r\n\\]\r\n

    (2)<\/strong><\/p>\r\n

    (1)<\/strong> \u306e\u7d50\u679c\u3088\u308a\r\n\\[\r\nt = \\dfrac{2-a}{3}\r\n\\]\r\n\u306a\u306e\u3067\r\n\\[\\begin{align}\r\nb^2 & = \\dfrac{1}{9} ( -8a^2+8a+16 ) \\\\\r\n& = \\dfrac{8}{9} \\left\\{ -\\left( a -\\dfrac{1}{2} \\right)^2 +\\dfrac{9}{4} \\right\\} \\\\\r\n& \\leqq \\dfrac{8}{9} \\cdot \\dfrac{9}{4} = 2\r\n\\end{align}\\]\r\n\u3088\u3063\u3066, \\(b\\) \u306f \\(a = \\dfrac{1}{2}\\) \u306e\u3068\u304d, \u6700\u5927\u5024 \\(\\underline{\\sqrt{2}}\\) \u3092\u3068\u308b.<\/p>\r\n","protected":false},"excerpt":{"rendered":"\u5ea7\u6a19\u5e73\u9762\u306b\u304a\u3044\u3066\u539f\u70b9\u3092\u4e2d\u5fc3\u3068\u3059\u308b\u534a\u5f84 \\(2\\) \u306e\u5186\u3092 \\(C _ 1\\) \u3068\u3057, \u70b9 \\((1,0)\\) \u3092\u4e2d\u5fc3\u3068\u3059\u308b\u534a\u5f84 \\(1\\) \u306e\u5186\u3092 \\(C _ 2\\) \u3068\u3059\u308b. \u307e\u305f, \u70b9 \\((a,b)\\) \u3092\u4e2d\u5fc3\u3068\u3059 … \u7d9a\u304d\u3092\u8aad\u3080 →<\/span><\/a>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[81],"tags":[149,15],"class_list":["post-554","post","type-post","status-publish","format-standard","hentry","category-tokyo_b_2009","tag-tokyo_b","tag-15"],"_links":{"self":[{"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/posts\/554","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/comments?post=554"}],"version-history":[{"count":0,"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/posts\/554\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/media?parent=554"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/categories?post=554"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.roundown.net\/nyushi\/wp-json\/wp\/v2\/tags?post=554"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}