{"id":4723,"date":"2020-12-03T15:33:05","date_gmt":"2020-12-03T06:33:05","guid":{"rendered":"https:\/\/www.educational-lounge.com\/?p=4723"},"modified":"2020-12-03T23:51:08","modified_gmt":"2020-12-03T14:51:08","slug":"%e3%80%90%e4%be%8b%e9%a1%8c%e3%81%a7%e5%ad%a6%e3%81%b6%e3%80%91%e9%81%8e%e5%8e%bb%e5%95%8f%e6%bc%94%e7%bf%92%e3%82%92%e9%80%9a%e3%81%97%e3%81%9f%e6%95%b0%e5%ad%a6%e2%85%b0a%e3%81%ae%e5%8b%89%e5%bc%b7","status":"publish","type":"post","link":"https:\/\/www.educational-lounge.com\/?p=4723","title":{"rendered":"\u3010\u4f8b\u984c\u3067\u5b66\u3076\u3011\u904e\u53bb\u554f\u6f14\u7fd2\u3092\u901a\u3057\u305f\u6570\u5b66\u2160A\u306e\u52c9\u5f37\u6cd5"},"content":{"rendered":"<p><script src=\"https:\/\/cdnjs.cloudflare.com\/ajax\/libs\/mathjax\/2.7.5\/MathJax.js?config=TeX-AMS_CHTML\" type=\"text\/javascript\">    \n    MathJax.Hub.Config({\n        HTML: [\"input\/TeX\",\"output\/HTML-CSS\"],\n        TeX: {\n               Macros: {\n                        bm: [\"\\\\boldsymbol{#1}\", 1]},\n               extensions: [\"AMSmath.js\",\"AMSsymbols.js\",\"color.js\"],\n               equationNumbers: { autoNumber: \"AMS\" } },\n        extensions: [\"tex2jax.js\"],\n        jax: [\"input\/TeX\",\"output\/HTML-CSS\"],\n        tex2jax: { inlineMath: [ ['$','$'], [\"\\\\(\",\"\\\\)\"] ],\n                   displayMath: [ ['$$','$$']], \n                   processEscapes: true },\n        \"HTML-CSS\": { availableFonts: [\"TeX\"],\n                      linebreaks: { automatic: true } }\n    });\n<\/script>\u3053\u3093\u306b\u3061\u306f\u3002\u6570\u5b66\u8b1b\u5e2b\u306e\u5927\u585a\u5fd7\u559c\u3067\u3059\u3002<\/p>\n<p>\u4eca\u56de\u306f\u5b9f\u969b\u306e\u5165\u8a66\u554f\u984c\u306e\u904e\u53bb\u554f\u3092\u5229\u7528\u3057\u3066\uff0c\u666e\u6bb5\u306e\u52c9\u5f37\u306b\u3069\u3046\u6d3b\u304b\u3057\u3066\u3044\u304f\u304b\u306b\u3064\u3044\u3066\u8a18\u4e8b\u3092\u66f8\u3044\u3066\u3044\u3053\u3046\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n<p>\u4eca\u307e\u3067\u306e\u8a18\u4e8b\u3067\u3082\u305f\u304f\u3055\u3093\u8a00\u3063\u3066\u3044\u308b\u3088\u3046\u306b\uff0c\u305f\u3060\u305d\u306e\u554f\u984c\u304c\u89e3\u3051\u308b\u3088\u3046\u306b\u306a\u308b\u3053\u3068\u3060\u3051\u3092\u76ee\u7684\u3068\u3057\u305f\u6f14\u7fd2\u306f\u5f97\u3089\u308c\u308b\u3082\u306e\u304c\u975e\u5e38\u306b\u5c11\u306a\u3044\u3067\u3059\u3002<br \/>\n1\u554f\u304b\u3089\u305f\u304f\u3055\u3093\u306e\u52b9\u679c\u3092\u5f97\u308b\u4f8b\u3092\u4e00\u3064\u7d39\u4ecb\u3057\u3066\u3044\u304d\u305f\u3044\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n<p>\u4eca\u56de\u306f\u4f59\u5f26\u5b9a\u7406\u3092\u77e5\u3063\u3066\u3044\u308b\u3053\u3068\u3092\u524d\u63d0\u3068\u3057\u307e\u3059\u3002<\/p>\n<h2 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u904e\u53bb\u554f\u306b\u53d6\u308a\u7d44\u3080\u524d\u306e\u7df4\u7fd2\u554f\u984c\uff11<\/h2>\n<p><img decoding=\"async\" class=\"alignnone wp-image-3753\" src=\"https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/07\/markus-spiske-IFCloi6PYOA-unsplash-300x200.jpg\" alt=\"\" width=\"540\" height=\"360\" srcset=\"https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/07\/markus-spiske-IFCloi6PYOA-unsplash-300x200.jpg 300w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/07\/markus-spiske-IFCloi6PYOA-unsplash-1024x683.jpg 1024w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/07\/markus-spiske-IFCloi6PYOA-unsplash-768x512.jpg 768w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/07\/markus-spiske-IFCloi6PYOA-unsplash-1536x1024.jpg 1536w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/07\/markus-spiske-IFCloi6PYOA-unsplash-2048x1365.jpg 2048w\" sizes=\"(max-width: 540px) 100vw, 540px\" \/><br \/>\n\u307e\u305a\u306f\u6b21\u306e\u554f\u984c\u3092\u89e3\u3044\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #f3f3f3;\">\u5186\u306b\u5185\u63a5\u3059\u308b\u56db\u89d2\u5f62$\\text{ABCD}$\u306b\u304a\u3044\u3066\uff0c$\\text{AB}=3\uff0c \\text{BC}=7\uff0c \\text{CD}=7\uff0c \\text{DA}=5$\u3067\u3042\u308b\u3068\u3059\u308b\u3002\u3053\u306e\u3068\u304d\uff0c$\\text{BC}$\u3092\u6c42\u3081\u3088\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u7df4\u7fd2\u554f\u984c1\u306e\u89e3\u7b54\u89e3\u8aac<\/h3>\n<p>\u3053\u306e\u554f\u984c\u306e\u6a21\u7bc4\u89e3\u7b54\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">$\\theta=\\angle\\text{BAD}$\u3068\u304a\u304f\u3068\uff0c\u56db\u89d2\u5f62$\\text{ABCD}$\u304c\u5186\u306b\u5185\u63a5\u3057\u3066\u3044\u308b\u3053\u3068\u304b\u3089\uff0c$\\angle\\text{BCD}=180^\\circ<br \/>\n-\\theta$\u3068\u308f\u304b\u308b\u3002\u3053\u3053\u3067\u3001$\\triangle\\text{ABD}$\u3068$\\triangle\\text{BCD}$\u3067\u4f59\u5f26\u5b9a\u7406\u3092\u7528\u3044\u308b\u3068\uff0c<br \/>\n\\begin{cases}<br \/>\n\\text{BD}^2 =\\text{AB}^2 +\\text{AD}^2 -2\u00d7\\text{AB}\u00d7\\text{AD}\u00d7\\cos\\theta\\\\<br \/>\n\\text{BD}^2 =\\text{CB}^2 +\\text{CD}^2 -2\u00d7\\text{CB}\u00d7\\text{CD}\u00d7\\cos(180^\\circ -\\theta)\\\\<br \/>\n\\end{cases}<br \/>\n\u3068\u304b\u3051\u308b\u3002\u3053\u3053\u3067\uff0c$\\cos(180^\\circ -\\theta)=-\\cos\\theta$\u3067\u3042\u308b\u3053\u3068\u3092\u5229\u7528\u3059\u308b\u3068\uff0c<br \/>\n\\begin{cases}<br \/>\n\\text{BD}^2 =\\text{AB}^2 +\\text{AD}^2 -2\u00d7\\text{AB}\u00d7\\text{AD}\u00d7\\cos\\theta\\\\<br \/>\n\\text{BD}^2 =\\text{CB}^2 +\\text{CD}^2 +2\u00d7\\text{CB}\u00d7\\text{CD}\u00d7\\cos\\theta\\\\<br \/>\n\\end{cases}<br \/>\n\u3068\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u308b\u304b\u3089\uff0c<br \/>\n$$\\text{AB}^2 +\\text{AD}^2 -2\u00d7\\text{AB}\u00d7\\text{AD}\u00d7\\cos\\theta=\\text{CB}^2 +\\text{CD}^2 +2\u00d7\\text{CB}\u00d7\\text{CD}\u00d7\\cos\\theta$$<br \/>\n\u3068\u306a\u308a\uff0c\u305d\u308c\u305e\u308c\u306e\u9577\u3055\u3092\u4ee3\u5165\u3057\u3066\u8a08\u7b97\u3092\u9032\u3081\u308b\u3068\uff0c$\\cos\\theta=-\\frac{1}{2}$\u3092\u5f97\u308b\u3002\u3088\u3063\u3066\uff0c<br \/>\n$$\\text{BD} ^2 =\\text{AB}^2 +\\text{AD}^2 -2\u00d7\\text{AB}\u00d7\\text{AD}\u00d7\\cos\\theta=3^2 +5^2 -2\u00d73\u00d75\u00d7(-\\frac{1}{2})=49$$<br \/>\n\u3068\u306a\u308a\uff0c$\\text{BD}=7$\u3092\u5f97\u308b\u3002<\/p>\n<p>\u3053\u306e\u554f\u984c\u306f\u6559\u79d1\u66f8\u306e\u4f8b\u984c\u306b\u3082\u3088\u304f\u3042\u308b\u30ec\u30d9\u30eb\u306e\u554f\u984c\u3067\uff0c\u53d7\u9a13\u751f\u3067\u3042\u308c\u3070\u304b\u306a\u308a\u306e\u4eba\u304c\u89e3\u3051\u308b\u30ec\u30d9\u30eb\u306e\u554f\u984c\u3067\u3059\u3002<\/p>\n<p>\u3057\u304b\u3057\u89e3\u304d\u65b9\u3092\u305f\u3060\u899a\u3048\u3066\u3044\u308b\u3060\u3051\u3067\u306f\uff0c\u6b21\u306e\u554f\u984c\u3068\u3053\u306e\u554f\u984c\u304c\uff0c\u5b9f\u306f\u5168\u304f\u540c\u3058\u30c6\u30fc\u30de\u306e\u554f\u984c\u3067\u3042\u308b\u3068\u3044\u3046\u3053\u3068\u306b\u6c17\u3065\u304f\u3053\u3068\u304c\u3067\u304d\u305a\uff0c\u624b\u3092\u9032\u3081\u308b\u3053\u3068\u304c\u3067\u304d\u306a\u3044\u72b6\u6cc1\u306b\u9665\u3063\u3066\u3057\u307e\u3046\u53ef\u80fd\u6027\u304c\u975e\u5e38\u306b\u9ad8\u3044\u3067\u3059\u3002<\/p>\n<p>&nbsp;<\/p>\n<h2 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u904e\u53bb\u554f\u306b\u53d6\u308a\u7d44\u3080\u524d\u306e\u7df4\u7fd2\u554f\u984c\uff12<\/h2>\n<p><img decoding=\"async\" class=\"alignnone wp-image-3504\" src=\"https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/05\/green-chameleon-s9CC2SKySJM-unsplash-300x200.jpg\" alt=\"\" width=\"540\" height=\"360\" srcset=\"https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/05\/green-chameleon-s9CC2SKySJM-unsplash-300x200.jpg 300w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/05\/green-chameleon-s9CC2SKySJM-unsplash-1024x683.jpg 1024w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/05\/green-chameleon-s9CC2SKySJM-unsplash-768x512.jpg 768w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/05\/green-chameleon-s9CC2SKySJM-unsplash-1536x1024.jpg 1536w, https:\/\/www.educational-lounge.com\/wp-content\/uploads\/2020\/05\/green-chameleon-s9CC2SKySJM-unsplash-2048x1365.jpg 2048w\" sizes=\"(max-width: 540px) 100vw, 540px\" \/><br \/>\n\u6b21\u306e\u554f\u984c\u3092\u89e3\u3044\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #f3f3f3;\">$\\triangle\\text{ABC}$\u306b\u304a\u3044\u3066\uff0c$\\text{BC}$\u306e\u4e2d\u70b9\u3092$\\text{D}$\u3068\u3059\u308b\u3002\u3053\u306e\u3068\u304d\uff0c\u4ee5\u4e0b\u306e\u95a2\u4fc2\u5f0f\u304c\u6210\u308a\u7acb\u3064\u3053\u3068\u3092\u793a\u305b\u3002$$\\text{AB}^2 +\\text{AC}^2 =2(\\text{AD}^2 +\\text{BD}^2 )$$<\/p>\n<p>\u3069\u3046\u3067\u3057\u3087\u3046\u304b\u3002<\/p>\n<p>\u521d\u898b\u3067\u306f\u306a\u304b\u306a\u304b\u624b\u5f37\u3044\u3068\u601d\u3044\u307e\u3059\u304c\uff0c\u5148\u307b\u3069\u306e\u554f\u984c\u304b\u3089\u3057\u3063\u304b\u308a\u3068\u91cd\u8981\u4e8b\u9805\u3092\u8eab\u306b\u3064\u3051\u3066\u3044\u308c\u3070\u81ea\u7136\u3068\u30b4\u30fc\u30eb\u306b\u305f\u3069\u308a\u7740\u304d\u307e\u3059\u3002<br \/>\n\u8a73\u3057\u304f\u8a71\u3057\u3066\u3044\u3053\u3046\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u7df4\u7fd2\u554f\u984c1\u3067\u4e00\u756a\u91cd\u8981\u3060\u3063\u305f\u3053\u3068<\/h3>\n<p>\u5b9f\u306f\u554f\u984c1\u3067\u4e00\u756a\u91cd\u8981\u306a\u306e\u306f\uff0c<\/p>\n<blockquote><p>\u300c\u5186\u306b\u5185\u63a5\u3059\u308b\u56db\u89d2\u5f62\u306e\u554f\u984c\u306f\u3053\u3046\u89e3\u304f\u300d<\/p><\/blockquote>\n<p>\u3067\u306f\u306a\u304f\uff0c<\/p>\n<blockquote><p>\u300c$\\cos(180^\\circ -\\theta)=-\\cos\\theta$\u304c\u6210\u308a\u7acb\u3064\u3053\u3068\u300d<\/p><\/blockquote>\n<p>\u306a\u306e\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u95a2\u4fc2\u5f0f\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u306b\u3088\u308a\uff0c\u300c\u9055\u3046\u4e09\u89d2\u5f62\u3067\u4f59\u5f26\u5b9a\u7406\u306e\u5f0f\u3092\u7acb\u3066\u3066\u3082\uff0c\u5f8c\u306e\u30ab\u30bf\u30de\u30ea\u306b\u3064\u3044\u3066\u3044\u308b\u4e09\u89d2\u6bd4\u304c\u4e21\u65b9\u3068\u3082$\\cos\\theta$\u3068\u306a\u308a\uff0c\u3068\u3066\u3082\u51e6\u7406\u3057\u3084\u3059\u3044\u5f62\u306b\u306a\u308b\u300d\u3068\u3044\u3046\u3053\u3068\u3053\u305d\uff0c\u3053\u306e\u554f\u984c\u304b\u3089\u5b66\u3076\u3079\u304d\u4e8b\u9805\u306a\u306e\u3067\u3059\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">\u307e\u3068\u3081\u308b\u3068\uff0c$\\theta$\u3068$180^\\circ -\\theta$\u306e\u30da\u30a2\u3092\u898b\u3064\u3051\u305f\u3089\uff0c\u305d\u306e2\u3064\u306e\u89d2\u5ea6\u3092\u7528\u3044\u3066\u4f59\u5f26\u5b9a\u7406\u306e\u5f0f\u3092\u7acb\u3066\u308b\u3068\u7d50\u5c40\u304d\u308c\u3044\u306a\u95a2\u4fc2\u5f0f\u3068\u306a\u308a\u51e6\u7406\u3057\u3084\u3059\u304f\u306a\u308b\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u985e\u306e\u554f\u984c\u7fa4\u306e\u4e2d\u306b\uff0c\u5186\u306b\u5185\u63a5\u3059\u308b\u56db\u89d2\u5f62\u306e\u554f\u984c\u304c\u542b\u307e\u308c\u3066\u3044\u308b\u306e\u3067\u3059\u3002<br \/>\n\u5186\u306b\u5185\u63a5\u3059\u308b\u56db\u89d2\u5f62\u306e\u5185\u89d2\u306b\u306f\uff0c$\\theta$\u3068$180^\\circ -\\theta$\u306e\u30da\u30a2\u304c2\u7d44\u3082\u3042\u308a\u307e\u3059\u304b\u3089\u5f53\u7136\u4f59\u5f26\u5b9a\u7406\u306e\u5f0f\u30922\u672c\u7acb\u3066\u3066\u307f\u3088\u3046\u304b\u3068\u3044\u3046\u8a71\u306b\u306a\u308b\u308f\u3051\u3067\u3059\u3002<\/p>\n<h3 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u554f\u984c2\u306e\u89e3\u8aac<\/h3>\n<p>\u3067\u306f\u4eca\u56de\u306e\u554f\u984c\u3067\u306f\u3069\u3046\u3067\u3057\u3087\u3046\u304b\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">$\\theta$\u3068$180^\\circ -\\theta$\u306e\u30da\u30a2\u306f\uff0c\u5186\u306b\u5185\u63a5\u3059\u308b\u56db\u89d2\u5f62\u306b\u3057\u304b\u73fe\u308c\u306a\u3044\u308f\u3051\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<br \/>\n\u4e00\u76f4\u7dda\u4e0a\u306b\u4e26\u30762\u3064\u306e\u89d2\u3082\uff0c$\\theta$\u3068$180^\\circ -\\theta$\u306e\u30da\u30a2\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u3053\u3053\u306b\u7740\u76ee\u3057\u305f\u3082\u306e\u304c\u4ee5\u4e0b\u306e\u89e3\u7b54\u3067\u3059\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">$\\theta=\\angle\\text{ADB}$\u3068\u304a\u304f\u3068\uff0c$\\angle\\text{ADC}=180^\\circ -\\theta$\u3068\u304b\u3051\u308b\u3002<br \/>\n$\\triangle\\text{ADB}$\u3068$\\triangle\\text{ADC}$\u3067\u4f59\u5f26\u5b9a\u7406\u3092\u7528\u3044\u308b\u3068\uff0c<br \/>\n\\begin{cases}<br \/>\n\\text{AB}^2 =\\text{AD}^2 + \\text{BD}^2 -2\u00d7\\text{AD} \u00d7\\text{BD} \u00d7\\cos\\theta\\\\<br \/>\n\\text{AC}^2 =\\text{AD}^2 + \\text{CD}^2 -2\u00d7\\text{AD}<br \/>\n\u00d7\\text{CD} \u00d7\\cos(180^\\circ<br \/>\n-\\theta)\\\\<br \/>\n\\end{cases}<br \/>\n\u3092\u5f97\u308b\u3002\u3053\u3053\u3067\uff0c$\\cos(180^\\circ -\\theta)=-\\cos\\theta$\u3067\u3042\u308b\u3053\u3068\u3068\uff0c$\\text{BD}=\\text{CD}$\u3067\u3042\u308b\u3053\u3068\u3092\u5229\u7528\u3059\u308b\u3068\uff0c<br \/>\n\\begin{cases}<br \/>\n\\text{AB}^2 =\\text{AD}^2 + \\text{BD}^2 -2\u00d7\\text{AD}\u00d7\\text{BD} \u00d7\\cos\\theta\\\\<br \/>\n\\text{AC}^2 =\\text{AD}^2 + \\text{BD}^2 +2\u00d7\\text{AD}\u00d7\\text{BD} \u00d7\\cos\\theta\\\\<br \/>\n\\end{cases}<br \/>\n\u3068\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u308b\u3002\u8fba\u3005\u52a0\u3048\u308b\u3068\uff0c<br \/>\n$$\\text{AB}^2 +\\text{AC}^2 =2\\text{AD}^2 +2\\text{BD}^2$$<br \/>\n\u3068\u306a\u308a\uff0c\u53f3\u8fba\u30922\u3067\u304f\u304f\u308b\u3053\u3068\u306b\u3088\u308a\uff0c<br \/>\n$$\\text{AB}^2 +\\text{AC}^2 =2(\\text{AD}^2 +\\text{BD}^2 )$$<br \/>\n\u3092\u5f97\u308b\u3002<\/p>\n<p>\u3069\u3046\u3067\u3057\u3087\u3046\u304b\u3002<br \/>\n\u30da\u30a2\u3092\u898b\u3064\u3051\u3066\u3057\u307e\u3063\u305f\u5f8c\u306f\u307b\u3068\u3093\u3069\u540c\u3058\u8a08\u7b97\u3067\u3057\u305f\u306d\u3002<\/p>\n<p>\u3082\u3046\u3053\u308c\u3089\u304c\u7570\u7a2e\u306e\u554f\u984c\u3060\u3068\u601d\u3046\u4eba\u306f\u3044\u306a\u3044\u3068\u601d\u3044\u307e\u3059\u3002<br \/>\n\u3057\u3063\u304b\u308a\u3068\u3057\u305f\u3068\u3053\u308d\u306b\u7740\u76ee\u3059\u308b\u3068\uff0c\u898b\u305f\u76ee\u304c\u5168\u304f\u9055\u3046\u554f\u984c\u3067\u3082\u540c\u3058\u3088\u3046\u306a\u8003\u3048\u65b9\u3067\u3057\u3063\u304b\u308a\u3068\u89e3\u304f\u3053\u3068\u304c\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">\u3061\u306a\u307f\u306b\u3053\u306e\u554f\u984c\u3067\u8a3c\u660e\u3057\u305f\u7b49\u5f0f\u306f\u4e2d\u7dda\u5b9a\u7406\u3068\u547c\u3070\u308c\u3066\u304a\u308a\uff0c\u975e\u5e38\u306b\u6709\u540d\u306a\u7d50\u679c\u3067\u3059\u3002<br \/>\n\u899a\u3048\u3066\u3044\u308c\u3070\u4f7f\u3063\u3066\u3082\u5927\u4e08\u592b\u3067\u3059\u3002<\/p>\n<h2 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u5b9f\u969b\u306e\u5165\u8a66\u554f\u984c\u3092\u89e3\u3044\u3066\u307f\u308b<\/h2>\n<p>\u3067\u306f\u6700\u5f8c\u306b\uff0c\u5b9f\u969b\u306e\u5165\u8a66\u554f\u984c\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #f3f3f3;\">\u4e09\u89d2\u3059\u3044$\\text{ABCD}$\u306b\u304a\u3044\u3066\u8fba$\\text{CD}$\u306f\u5e95\u9762$\\text{ABC}$\u306b\u5782\u76f4\u3067\u3042\u308b\u3002$\\text{AB}=3$\u3067\uff0c\u8fba$\\text{AB}$\u4e0a\u306e2\u70b9$\\text{E}\uff0c \\text{F}$\u306f\uff0c$\\text{AE}=\\text{EF}=\\text{FB}=1$\u3092\u307f\u305f\u3057\uff0c$\\angle\\text{DAC}=30^\\circ, \\angle\\text{DEC}=45^\\circ, \\angle\\text{DBC}=60^\\circ$\u3067\u3042\u308b\u3002<br \/>\n\uff081\uff09\u8fba$\\text{CD}$\u306e\u9577\u3055\u3092\u6c42\u3081\u3088\u3002<br \/>\n\uff082\uff09$\\theta=\\angle\\text{DFC}$\u3068\u304a\u304f\u3068\u304d\uff0c$\\cos\\theta$\u3092\u6c42\u3081\u3088\u3002<\/p>\n<h3 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u5165\u8a66\u554f\u984c(1)\u306e\u89e3\u8aac<\/h3>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">\u307e\u305a\u306f$x=\\text{CD}$\u3068\u304a\u3044\u3066\u307f\u307e\u3057\u3087\u3046\u3002<br \/>\n\u3059\u308b\u3068\uff0c$\\angle\\rm DAC =30^\\circ ,\\angle\\rm DEC =45^\\circ ,\\angle\\rm DBC =60^\\circ$\u3067\u3042\u308b\u3053\u3068\u3068\u8fba$\\text{CD}$\u304c\u5e95\u9762$\\text{ABC}$\u306b\u5782\u76f4\u3067\u3042\u308b\u3053\u3068\u304b\u3089\uff0c<br \/>\n$$\\text{DA}=2x, \\text{DE}=\\sqrt{2x}, \\text{DB}=\\frac{2}{\\sqrt{3}}x$$<br \/>\n\u3068\u308f\u304b\u308a\u307e\u3059\u3002<\/p>\n<p>\u4f55\u304b\u95a2\u4fc2\u5f0f\u30921\u672c\u7acb\u3066\u308b\u3053\u3068\u304c\u3067\u304d\u308c\u3070$x$\u304c\u6c42\u307e\u308a\u305d\u3046\u3067\u3059\u3002<br \/>\n\u3053\u3053\u3067\uff0c$\\triangle\\rm DAB$\u306b\u7740\u76ee\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<br \/>\n\u4f55\u304b\u3067\u304d\u305d\u3046\u306a\u3053\u3068\u306f\u306a\u3044\u3067\u3057\u3087\u3046\u304b\u3002<\/p>\n<p>\u3053\u3053\u307e\u3067\u6765\u308b\u3068\u3082\u3046\u7c21\u5358\u306b\u6c17\u3065\u304f\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<br \/>\n$\\angle\\text{DEA}$\u3068$\\angle\\text{DEB}$\u304c$\\theta$\u3068$180^\\circ -\\theta$\u306e\u30da\u30a2\u306b\u306a\u3063\u3066\u3044\u308b\u308f\u3051\u3067\u3059\u3002<br \/>\n\u3053\u308c\u306f\u4f59\u5f26\u5b9a\u7406\u3092\u4f7f\u308f\u3056\u308b\u3092\u5f97\u306a\u3044\u3067\u3059\u306d(\u7b11)\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">$\\theta=\\angle\\rm DEA$\u3068\u304a\u304f\u3068\uff0c$\\angle\\rm DEB =180^\\circ -\\theta$\u3067\u3042\u308b\u3002<br \/>\n$\\triangle\\text{DEA}$\u3068$\\triangle\\text{DEB}$\u3067\u4f59\u5f26\u5b9a\u7406\u3092\u7528\u3044\u308b\u3068\uff0c<br \/>\n\\begin{cases}<br \/>\n\\text{DA}^2 =\\text{DE}^2 + \\text{AE}^2 -2\u00d7\\text{DE}\u00d7\\text{AE} \u00d7\\cos\\theta\\\\<br \/>\n\\text{DB}^2 =\\text{DE}^2 + \\text{BE}^2 -2\u00d7\\text{DE}\u00d7\\text{BE}\u00d7\\cos(180^\\circ -\\theta)\\\\<br \/>\n\\end{cases}\u3092\u5f97\u308b\u3002\u3053\u308c\u3089\u306b\u65e2\u77e5\u306e\u60c5\u5831\u3092\u4ee3\u5165\u3059\u308b\u3068\uff0c<br \/>\n\\begin{cases}<br \/>\n(2x)^2 =(\\sqrt{2x})^2 +1^2 -2\u00d7\\sqrt{2x}\u00d71\u00d7\\cos\\theta\\\\<br \/>\n(\\frac{2}{\\sqrt{3}}x)^2 =(\\sqrt{2x})^2 +2^2 +2\u00d7\\sqrt{2x}\u00d72\u00d7\\cos\\theta\\\\<br \/>\n\\end{cases}\u6574\u7406\u3057\u3066\uff0c\\begin{cases}<br \/>\n2x^2 =1-2\\sqrt{2x}\\cos\\theta\\\\<br \/>\n-\\frac{2}{3}x^2 =4+4\\sqrt{2x}\\cos\\theta\\\\<br \/>\n\\end{cases}<br \/>\n$\\cos\\theta$\u3092\u6d88\u53bb\u3057\u3066\uff0c$\\frac{10}{3}x^2<br \/>\n=6$\u3068\u306a\u308a\uff0c$\\text{CD}=\\frac{3}{\\sqrt{5}}=\\frac{3\\sqrt{5}}{5}$\u3092\u5f97\u308b\u3002<\/p>\n<h3 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u5165\u8a66\u554f\u984c(2)\u306e\u89e3\u8aac<\/h3>\n<p>\u3053\u3053\u307e\u3067\u6765\u308b\u3068\u3082\u3046\u304a\u307e\u3051\u3067\u3059\u3002<br \/>\n$\\triangle\\rm DEB$\u306b\u7740\u76ee\u3059\u308b\u3068\uff0c\u554f\u984c2\u3067\u8a3c\u660e\u3057\u305f\u4e2d\u7dda\u5b9a\u7406\u304c\u4f7f\u3048\u305d\u3046\u3067\u3059\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">\u4e2d\u7dda\u5b9a\u7406\u3092\u7528\u3044\u308b\u3068\uff0c<br \/>\n$$\\text{DE}^2 +\\text{DB}^2 =2(\\text{DF}^2 +\\text{EF} ^2)$$<br \/>\n\u3068\u306a\u308a\uff0c\u3053\u306e\u5f0f\u304b\u3089\uff0c$\\text{DE}^2 =\\frac{5}{3}x^2 -1=2$\u3092\u5f97\u308b\u3002<br \/>\n\u3088\u3063\u3066$\\rm DF =\\sqrt{2}$\u3068\u308f\u304b\u308b\u3002<br \/>\n\u3042\u3068\u306f$\\triangle\\rm DFC$\u306b\u7740\u76ee\u3057\u3066\uff0c<br \/>\n$$\\sin\\theta=\\frac{\\text{DF}}{\\text{CD}}=\\frac{3}{\\sqrt{10}}$$<br \/>\n\u3068\u308f\u304b\u308b\u304b\u3089\uff0c\u3053\u3053\u304b\u3089$\\cos\\theta=\\frac{1}{\\sqrt{10}}$\u3092\u5f97\u308b\u3002<\/p>\n<p>\uff081\uff09\u3067\u4e2d\u7dda\u5b9a\u7406\u306e\u8a3c\u660e\u306e\u4ed5\u7d44\u307f\u304c\u5206\u304b\u3063\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3057\uff0c\u5206\u304b\u3063\u3066\u3044\u308b\u3088\u3046\u3067\u3042\u308c\u3070\uff082\uff09\u3067\u4e2d\u7dda\u5b9a\u7406\u3092\u4f7f\u3063\u3066\u697d\u3057\u3066\u3082\u3044\u3044\u3088\uff0c\u3068\u3044\u3046\u30e1\u30c3\u30bb\u30fc\u30b8\u304c\u805e\u3053\u3048\u3066\u304d\u305d\u3046\u306a\u554f\u984c\u3067\u3057\u305f\u306d\u3002<\/p>\n<h2 style=\"padding: .25em 0.5em .75em; border-left: 6px solid #3300ff; border-bottom: 1px solid #ccc;\">\u307e\u3068\u3081<\/h2>\n<p>\u4ee5\u4e0a\u306e\u3088\u3046\u306b\uff0c\u5165\u8a66\u554f\u984c\u3068\u3044\u3046\u306e\u306f\u5fc5\u305a\u57fa\u790e\u304b\u3089\u306e\u5fdc\u7528\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<p style=\"border: 1.5px dotted #ffffff; padding: 10px; border-radius: 0px; background: #efefff;\">\u666e\u6bb5\u304b\u3089\u3057\u3063\u304b\u308a\u3068\u3057\u305f\u8996\u70b9\u3092\u6301\u3063\u3066\u52c9\u5f37\u3057\u3066\u3044\u304f\u3068\uff0c\u52b9\u7387\u3088\u304f\u5165\u8a66\u554f\u984c\u3092\u89e3\u304f\u529b\u3092\u3064\u3051\u3066\u3044\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\u4eca\u56de\u306e\u984c\u6750\u306f\u3042\u304f\u307e\u3067\u4e00\u4f8b\u3067\u3059\u3002<br \/>\n\u666e\u6bb5\u306e\u52c9\u5f37\u306e\u53c2\u8003\u306b\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<p>\u3067\u306f\u4eca\u56de\u306f\u3053\u306e\u8fba\u3067\u5931\u793c\u3057\u307e\u3059\u3002<br \/>\n\u307e\u305f\u6b21\u306e\u8a18\u4e8b\u3067\u304a\u4f1a\u3044\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n","protected":false},"excerpt":{"rendered":"<p>\u3053\u3093\u306b\u3061\u306f\u3002\u6570\u5b66\u8b1b\u5e2b\u306e\u5927\u585a\u5fd7\u559c\u3067\u3059\u3002 \u4eca\u56de\u306f\u5b9f\u969b\u306e\u5165\u8a66\u554f\u984c\u306e\u904e\u53bb\u554f\u3092\u5229\u7528\u3057\u3066\uff0c\u666e\u6bb5\u306e\u52c9\u5f37\u306b\u3069\u3046\u6d3b\u304b\u3057\u3066\u3044\u304f\u304b\u306b\u3064\u3044\u3066\u8a18\u4e8b\u3092\u66f8\u3044\u3066\u3044\u3053\u3046\u3068\u601d\u3044\u307e\u3059\u3002 \u4eca\u307e\u3067\u306e\u8a18\u4e8b\u3067\u3082\u305f\u304f\u3055\u3093\u8a00\u3063\u3066\u3044\u308b\u3088\u3046\u306b\uff0c\u305f\u3060\u305d\u306e\u554f\u984c\u304c\u89e3\u3051\u308b\u3088\u3046\u306b\u306a\u308b\u2026<\/p>\n","protected":false},"author":17,"featured_media":3751,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,144,5],"tags":[],"class_list":["post-4723","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-6","category-a","category-5"],"_links":{"self":[{"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/posts\/4723","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4723"}],"version-history":[{"count":76,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/posts\/4723\/revisions"}],"predecessor-version":[{"id":4834,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/posts\/4723\/revisions\/4834"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=\/wp\/v2\/media\/3751"}],"wp:attachment":[{"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4723"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4723"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.educational-lounge.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4723"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}