{"id":11410,"date":"2022-12-02T14:53:41","date_gmt":"2022-12-02T05:53:41","guid":{"rendered":"https:\/\/hatsudy.com\/jp\/?p=11410"},"modified":"2023-08-21T00:36:59","modified_gmt":"2023-08-20T15:36:59","slug":"trigonometric-equations6","status":"publish","type":"post","link":"https:\/\/hatsudy.com\/jp\/trigonometric-equations6.html","title":{"rendered":"\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\uff1a\u516c\u5f0f\u306e\u5c0e\u51fa\u65b9\u6cd5\u3068\u554f\u984c\u306e\u89e3\u304d\u65b9"},"content":{"rendered":"\n<p>\u4e09\u89d2\u95a2\u6570\u3067\u306f\u3001\u548c\u3068\u7a4d\u3092\u5909\u63db\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u8db3\u3057\u7b97\u3092\u304b\u3051\u7b97\u306b\u5909\u3048\u305f\u308a\u3001\u304b\u3051\u7b97\u3092\u8db3\u3057\u7b97\u306b\u5909\u3048\u305f\u308a\u3067\u304d\u308b\u306e\u3067\u3059\u3002\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u306b\u3088\u308a\u3001\u5f0f\u3092\u5909\u5f62\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u899a\u3048\u3066\u306f\u3044\u3051\u307e\u305b\u3093\u3002\u52a0\u6cd5\u5b9a\u7406\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u306b\u3088\u308a\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u5f0f\u3092\u4f5c\u308a\u307e\u3057\u3087\u3046\u3002\u52a0\u6cd5\u5b9a\u7406\u304c\u95a2\u308f\u308b\u516c\u5f0f\u306f\u591a\u3044\u305f\u3081\u3001\u3059\u3079\u3066\u306e\u516c\u5f0f\u3092\u899a\u3048\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u516c\u5f0f\u3092\u5c0e\u51fa\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u306a\u304a\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u5229\u7528\u3059\u308c\u3070\u3001\u8907\u96d1\u306a\u4e09\u89d2\u95a2\u6570\u306e\u8a08\u7b97\u3092\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u305f\u308a\u3001\u8a3c\u660e\u554f\u984c\u3092\u89e3\u3051\u305f\u308a\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u305d\u308c\u3067\u306f\u3001\u3069\u306e\u3088\u3046\u306b\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u4f5c\u308c\u3070\u3044\u3044\u306e\u3067\u3057\u3087\u3046\u304b\u3002\u307e\u305f\u3001\u3069\u306e\u3088\u3046\u306b\u4e09\u89d2\u95a2\u6570\u306e\u554f\u984c\u3092\u89e3\u3051\u3070\u3044\u3044\u306e\u3067\u3057\u3087\u3046\u304b\u3002\u4e09\u89d2\u95a2\u6570\u306e\u8db3\u3057\u7b97\u3068\u304b\u3051\u7b97\u3092\u5909\u5f62\u3059\u308b\u65b9\u6cd5\u3084\u8a08\u7b97\u65b9\u6cd5\u3092\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<h2>\u52a0\u6cd5\u5b9a\u7406\u3092\u5229\u7528\u3057\u3001\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u5c0e\u51fa\u3059\u308b<\/h2>\n<p>\u4e09\u89d2\u95a2\u6570\u306b\u3064\u3044\u3066\u3001\u8db3\u3057\u7b97\u3068\u304b\u3051\u7b97\u3092\u5909\u63db\u3059\u308b\u305f\u3081\u306b\u306f\u3001\u516c\u5f0f\u3092\u5229\u7528\u3057\u306a\u3051\u308c\u3070\u3044\u3051\u307e\u305b\u3093\u3002\u307e\u305a\u3001\u304b\u3051\u7b97\u3092\u8db3\u3057\u7b97\u306b\u5909\u3048\u308b\u516c\u5f0f\u3092\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002\u516c\u5f0f\u306f\u4ee5\u4e0b\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(sin\u03b1cos\u03b2=\\displaystyle\\frac{1}{2}(sin(\u03b1+\u03b2)\\)\\(+sin(\u03b1-\u03b2))\\)<\/li>\n<li>\\(cos\u03b1sin\u03b2=\\displaystyle\\frac{1}{2}(sin(\u03b1+\u03b2)\\)\\(-sin(\u03b1-\u03b2))\\)<\/li>\n<li>\\(cos\u03b1cos\u03b2=\\displaystyle\\frac{1}{2}(cos(\u03b1+\u03b2)\\)\\(+cos(\u03b1-\u03b2))\\)<\/li>\n<li>\\(sin\u03b1sin\u03b2=-\\displaystyle\\frac{1}{2}(cos(\u03b1+\u03b2)\\)\\(-cos(\u03b1-\u03b2))\\)<\/li>\n<\/ul>\n<p>\u524d\u8ff0\u306e\u901a\u308a\u3001\u3053\u308c\u3089\u306e\u516c\u5f0f\u3092\u899a\u3048\u3066\u306f\u3044\u3051\u307e\u305b\u3093\u3002<span style=\"color: #0000ff;\">\u52a0\u6cd5\u5b9a\u7406\u3092\u7528\u3044\u3066\u516c\u5f0f\u306e\u5c0e\u51fa\u304c\u53ef\u80fd\u3067\u3042\u308b\u305f\u3081\u3001\u516c\u5f0f\u306e\u4f5c\u308a\u65b9\u3092\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/span>\u52a0\u6cd5\u5b9a\u7406\u3088\u308a\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(sin(\u03b1+\u03b2)=sin\u03b1cos\u03b2+cos\u03b1sin\u03b2\\) &#8211; \u2460<\/li>\n<li>\\(sin(\u03b1-\u03b2)=sin\u03b1cos\u03b2-cos\u03b1sin\u03b2\\) &#8211; \u2461<\/li>\n<\/ul>\n<p>\\(\u2460+\u2461\\)\u3088\u308a\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\\(sin(\u03b1+\u03b2)+sin(\u03b1-\u03b2)=2sin\u03b1cos\u03b2\\)<\/p>\n<p>\\(sin\u03b1cos\u03b2=\\displaystyle\\frac{1}{2}(sin(\u03b1+\u03b2)+sin(\u03b1-\u03b2))\\)<\/p>\n<p>\u3053\u3046\u3057\u3066\u3001\u516c\u5f0f\u3092\u5f97\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002\u307e\u305f\\(\u2460-\u2461\\)\u306b\u3088\u308a\u3001\u4ee5\u4e0b\u306e\u516c\u5f0f\u3092\u5f97\u3089\u308c\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(cos\u03b1sin\u03b2=\\displaystyle\\frac{1}{2}(sin(\u03b1+\u03b2)\\)\\(-sin(\u03b1-\u03b2))\\)<\/li>\n<\/ul>\n<p>\u6b21\u306b\u3001\u4ee5\u4e0b\u306e\u52a0\u6cd5\u5b9a\u7406\u3092\u5229\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<ul>\n<li>\\(cos(\u03b1+\u03b2)=cos\u03b1cos\u03b2-sin\u03b1sin\u03b2\\) &#8211; \u2462<\/li>\n<li>\\(cos(\u03b1-\u03b2)=cos\u03b1cos\u03b2+sin\u03b1sin\u03b2\\) &#8211; \u2463<\/li>\n<\/ul>\n<p>\\(\u2462+\u2463\\)\u306b\u3088\u308a\u3001\u4ee5\u4e0b\u306e\u516c\u5f0f\u3092\u5f97\u3089\u308c\u307e\u3059\u3002<\/p>\n<p>\\(cos(\u03b1+\u03b2)+cos(\u03b1-\u03b2)=2cos\u03b1cos\u03b2\\)<\/p>\n<p>\\(cos\u03b1cos\u03b2=\\displaystyle\\frac{1}{2}(cos(\u03b1+\u03b2)+cos(\u03b1-\u03b2))\\)<\/p>\n<p>\u3053\u3046\u3057\u3066\u3001\u516c\u5f0f\u3092\u5f97\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002\u540c\u69d8\u306b\\(\u2462-\u2463\\)\u306b\u3088\u308a\u3001\u4ee5\u4e0b\u306e\u516c\u5f0f\u3092\u5f97\u3089\u308c\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(sin\u03b1sin\u03b2=-\\displaystyle\\frac{1}{2}(cos(\u03b1+\u03b2)\\)\\(-cos(\u03b1-\u03b2))\\)<\/li>\n<\/ul>\n<p>\u7c21\u5358\u306a\u8a08\u7b97\u306b\u3088\u308a\u3001\u516c\u5f0f\u3092\u4f5c\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3053\u308c\u304c\u3001\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u899a\u3048\u308b\u5fc5\u8981\u304c\u306a\u3044\u7406\u7531\u3067\u3059\u3002<\/p>\n<h3>\u548c\u3092\u7a4d\u306b\u5909\u63db\u3059\u308b\u516c\u5f0f\u306e\u5c0e\u51fa<\/h3>\n<p>\u6b21\u306b\u3001\u8db3\u3057\u7b97\u3092\u304b\u3051\u7b97\u306b\u5909\u63db\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u3087\u3046\u3002\u5148\u307b\u3069\u306e\u516c\u5f0f\u3092\u5229\u7528\u3059\u308c\u3070\u3001\u5bb9\u6613\u306b\u516c\u5f0f\u3092\u4f5c\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\\(\u03b1+\u03b2=A\\)\u3001\\(\u03b1-\u03b2=B\\)\u3068\u3057\u307e\u3057\u3087\u3046\u3002\u3053\u306e\u5834\u5408\u3001\\(\u03b1=\\displaystyle\\frac{A+B}{2}\\)\u3067\u3042\u308a\u3001\\(\u03b2=\\displaystyle\\frac{A-B}{2}\\)\u3067\u3059\u3002\u305d\u3053\u3067\u3001\u5148\u307b\u3069\u306e\u516c\u5f0f\u306b\u4ee3\u5165\u3059\u308b\u3068\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(sin\\displaystyle\\frac{A+B}{2}cos\\displaystyle\\frac{A-B}{2}=\\displaystyle\\frac{1}{2}(sinA\\)\\(+sinB)\\)<\/li>\n<li>\\(cos\\displaystyle\\frac{A+B}{2}sin\\displaystyle\\frac{A-B}{2}=\\displaystyle\\frac{1}{2}(sinA\\)\\(-sinB)\\)<\/li>\n<li>\\(cos\\displaystyle\\frac{A+B}{2}cos\\displaystyle\\frac{A-B}{2}=\\displaystyle\\frac{1}{2}(cosA\\)\\(+cosB)\\)<\/li>\n<li>\\(sin\\displaystyle\\frac{A+B}{2}sin\\displaystyle\\frac{A-B}{2}=\\displaystyle\\frac{1}{2}(cosA\\)\\(-cosB)\\)<\/li>\n<\/ul>\n<p>\u5f0f\u3092\u6574\u7406\u3059\u308b\u3068\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(sinA+sinB=2sin\\displaystyle\\frac{A+B}{2}\\)\\(cos\\displaystyle\\frac{A-B}{2}\\)<\/li>\n<li>\\(sinA-sinB=2cos\\displaystyle\\frac{A+B}{2}\\)\\(sin\\displaystyle\\frac{A-B}{2}\\)<\/li>\n<li>\\(cosA+cosB=2cos\\displaystyle\\frac{A+B}{2}\\)\\(cos\\displaystyle\\frac{A-B}{2}\\)<\/li>\n<li>\\(cosA-cosB=-2sin\\displaystyle\\frac{A+B}{2}\\)\\(sin\\displaystyle\\frac{A-B}{2}\\)<\/li>\n<\/ul>\n<p>\u3053\u3046\u3057\u3066\u3001\u8db3\u3057\u7b97\u3092\u304b\u3051\u7b97\u3078\u5909\u63db\u3059\u308b\u305f\u3081\u306b\u5fc5\u8981\u306a\u516c\u5f0f\u3092\u5f97\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002\u8907\u96d1\u306a\u516c\u5f0f\u3067\u3042\u308b\u305f\u3081\u3001\u516c\u5f0f\u3092\u899a\u3048\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u516c\u5f0f\u3092\u4f5c\u308c\u308b\u3088\u3046\u306b\u306a\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<h2>\u516c\u5f0f\u3092\u5229\u7528\u3057\u3066\u8a08\u7b97\u554f\u984c\u3092\u89e3\u304f<\/h2>\n<p>\u305d\u308c\u3067\u306f\u3001\u516c\u5f0f\u3092\u5229\u7528\u3057\u3066\u8a08\u7b97\u554f\u984c\u3092\u89e3\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u3087\u3046\u3002\u4ee5\u4e0b\u306e\u554f\u984c\u306b\u3064\u3044\u3066\u3001\u5024\u3092\u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<ul>\n<li>\\(cos\\displaystyle\\frac{5\u03c0}{12}-cos\\displaystyle\\frac{\u03c0}{12}\\)<\/li>\n<\/ul>\n<p>\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u3068\u3001\u8a08\u7b97\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\\(cos\\displaystyle\\frac{5\u03c0}{12}-cos\\displaystyle\\frac{\u03c0}{12}\\)<\/p>\n<p>\\(=-2sin\\displaystyle\\frac{\\displaystyle\\frac{5\u03c0}{12}+\\displaystyle\\frac{\u03c0}{12}}{2}sin\\displaystyle\\frac{\\displaystyle\\frac{5\u03c0}{12}-\\displaystyle\\frac{\u03c0}{12}}{2}\\)<\/p>\n<p>\\(=-2sin\\displaystyle\\frac{\u03c0}{4}sin\\displaystyle\\frac{\u03c0}{6}\\)<\/p>\n<p>\\(=-2\u00b7\\displaystyle\\frac{1}{\\sqrt{2}}\u00b7\\displaystyle\\frac{1}{2}\\)<\/p>\n<p>\\(=-\\displaystyle\\frac{\\sqrt{2}}{2}\\)<\/p>\n<p>\u6b21\u306b\u3001\u5c11\u3057\u8907\u96d1\u306a\u5f0f\u3092\u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002\u4ee5\u4e0b\u306e\u5f0f\u306e\u5024\u306f\u4f55\u3067\u3057\u3087\u3046\u304b\u3002<\/p>\n<ul>\n<li>\\(sin20\u00b0sin40\u00b0sin80\u00b0\\)<\/li>\n<\/ul>\n<p>\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u8a08\u7b97\u3057\u307e\u3059\u3002<\/p>\n<p>\\(\\color{red}{sin20\u00b0sin40\u00b0}sin80\u00b0\\)<\/p>\n<p>\\(=-\\color{red}{\\displaystyle\\frac{1}{2}(cos60\u00b0-cos20\u00b0)}sin80\u00b0\\)<\/p>\n<p>\\(=-\\displaystyle\\frac{1}{2}\\left(\\displaystyle\\frac{1}{2}-cos20\u00b0\\right)sin80\u00b0\\)<\/p>\n<p>\\(=-\\displaystyle\\frac{1}{4}sin80\u00b0+\\displaystyle\\frac{1}{2}sin80\u00b0cos20\u00b0\\)<\/p>\n<p>\\(=-\\displaystyle\\frac{1}{4}sin80\u00b0+\\displaystyle\\frac{1}{4}(sin100\u00b0+sin60\u00b0)\\)<\/p>\n<p>\\(=-\\displaystyle\\frac{1}{4}sin80\u00b0+\\displaystyle\\frac{1}{4}sin(180\u00b0-100\u00b0)\\)\\(+\\displaystyle\\frac{1}{4}\u00b7\\displaystyle\\frac{\\sqrt{3}}{2}\\)<\/p>\n<p>\\(=-\\displaystyle\\frac{1}{4}sin80\u00b0+\\displaystyle\\frac{1}{4}sin80\u00b0+\\displaystyle\\frac{\\sqrt{3}}{8}\\)<\/p>\n<p>\\(=\\displaystyle\\frac{\\sqrt{3}}{8}\\)<\/p>\n<p>\u3053\u3046\u3057\u3066\u3001\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u306b\u3088\u3063\u3066\u7b54\u3048\u3092\u5f97\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n<h3>\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u8a3c\u660e\u554f\u984c<\/h3>\n<p>\u8a3c\u660e\u554f\u984c\u3092\u89e3\u304f\u3068\u304d\u306b\u3064\u3044\u3066\u3082\u3001\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u306f\u5f79\u306b\u7acb\u3061\u307e\u3059\u3002\u305d\u308c\u3067\u306f\u25b3ABC\u306b\u3064\u3044\u3066\u3001\u4ee5\u4e0b\u306e\u7b49\u5f0f\u304c\u6210\u308a\u7acb\u3064\u3053\u3068\u3092\u8a3c\u660e\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<ul>\n<li>\\(sinA+sinB+sinC\\)\\(=4cos\\displaystyle\\frac{A}{2}\u00b7cos\\displaystyle\\frac{B}{2}\u00b7cos\\displaystyle\\frac{C}{2}\\)<\/li>\n<\/ul>\n<p>\u4e09\u89d2\u5f62\u3067\u306f\u3059\u3079\u3066\u306e\u89d2\u3092\u8db3\u3059\u3068\\(\u03c0\\)\u306b\u306a\u308a\u307e\u3059\u3002\u305d\u306e\u305f\u3081\\(A+B+C=\u03c0\\)\u3067\u3042\u308a\u3001\\(C=\u03c0-(A+B)\\)\u3067\u3059\u3002\u305d\u306e\u305f\u3081\u3001\\(sinC\\)\u3092\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u5909\u63db\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\\(sinC=sin(\u03c0-(A+B))\\)<\/p>\n<p>\\(sinC=sin(A+B)\\)<\/p>\n<p>\u307e\u305f\\(cos\\displaystyle\\frac{C}{2}\\)\u306b\\(C=\u03c0-(A+B)\\)\u3092\u4ee3\u5165\u3059\u308b\u3068\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u8a08\u7b97\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\\(cos\\displaystyle\\frac{C}{2}\\)<\/p>\n<p>\\(=cos\\left(\\displaystyle\\frac{\u03c0}{2}-\\displaystyle\\frac{A+B}{2}\\right)\\)<\/p>\n<p>\\(=sin\\displaystyle\\frac{A+B}{2}\\)<\/p>\n<p>\u305d\u3053\u3067\u3001\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3084\u52a0\u6cd5\u5b9a\u7406\u3092\u5229\u7528\u3057\u3066\u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\\(sinA+sinB+sinC\\)<\/p>\n<p>\\(=\\color{red}{sinA+sinB}+sin(A+B)\\)<\/p>\n<p>\\(=\\color{red}{2sin\\displaystyle\\frac{A+B}{2}cos\\displaystyle\\frac{A-B}{2}}+sin(A+B)\\)<\/p>\n<p>\\(=2sin\\displaystyle\\frac{A+B}{2}cos\\displaystyle\\frac{A-B}{2}+sin2\u00b7\\displaystyle\\frac{A+B}{2}\\)<\/p>\n<p>\\(=2sin\\displaystyle\\frac{A+B}{2}cos\\displaystyle\\frac{A-B}{2}\\)\\(+2sin\\displaystyle\\frac{A+B}{2}cos\\displaystyle\\frac{A+B}{2}\\)\uff1a2\u500d\u89d2\u306e\u516c\u5f0f<\/p>\n<p>\\(=2sin\\displaystyle\\frac{A+B}{2}\\left(\\color{red}{cos\\displaystyle\\frac{A-B}{2}+cos\\displaystyle\\frac{A+B}{2}}\\right)\\)<\/p>\n<p>\\(=4sin\\displaystyle\\frac{A+B}{2}\u00b7cos\\displaystyle\\frac{A}{2}\u00b7cos\\left(-\\displaystyle\\frac{B}{2}\\right)\\)<\/p>\n<p>\\(=4cos\\displaystyle\\frac{A}{2}\u00b7cos\\displaystyle\\frac{B}{2}\u00b7cos\\displaystyle\\frac{C}{2}\\)<\/p>\n<p>\u3053\u3046\u3057\u3066\u3001\u8a3c\u660e\u554f\u984c\u3092\u89e3\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n<h3>\u516c\u5f0f\u3092\u7528\u3044\u3066\u4e09\u89d2\u65b9\u7a0b\u5f0f\u3092\u89e3\u304f<\/h3>\n<p>\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u306f\u4e09\u89d2\u65b9\u7a0b\u5f0f\u3092\u89e3\u304f\u3068\u304d\u306b\u3082\u5f79\u7acb\u3061\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u5f0f\u306b\u3064\u3044\u3066\u3001\\(0\u2266\u03b8\u2266\u03c0\\)\u3068\u306a\u308b\u03b8\u3092\u6c42\u3081\u307e\u3057\u3087\u3046\u3002<\/p>\n<ul>\n<li>\\(sin\u03b8+sin2\u03b8+sin3\u03b8+sin4\u03b8=0\\)<\/li>\n<\/ul>\n<p>\u516c\u5f0f\u3092\u5229\u7528\u3057\u3066\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u8a08\u7b97\u3057\u307e\u3059\u3002<\/p>\n<p>\\(sin4\u03b8+sin\u03b8=2sin\\displaystyle\\frac{5\u03b8}{2}cos\\displaystyle\\frac{3\u03b8}{2}\\)<\/p>\n<p>\\(sin3\u03b8+sin2\u03b8=2sin\\displaystyle\\frac{5\u03b8}{2}cos\\displaystyle\\frac{\u03b8}{2}\\)<\/p>\n<p>\u305d\u306e\u305f\u3081\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\\(sin\u03b8+sin2\u03b8+sin3\u03b8+sin4\u03b8=0\\)<\/p>\n<p>\\(2sin\\displaystyle\\frac{5\u03b8}{2}cos\\displaystyle\\frac{3\u03b8}{2}\\)\\(+2sin\\displaystyle\\frac{5\u03b8}{2}cos\\displaystyle\\frac{\u03b8}{2}\\)\\(=0\\)<\/p>\n<p>\\(2sin\\displaystyle\\frac{5\u03b8}{2}\\left(cos\\displaystyle\\frac{3\u03b8}{2}+cos\\displaystyle\\frac{\u03b8}{2}\\right)=0\\)<\/p>\n<p>\\(0\u2266\u03b8\u2266\u03c0\\)\u3067\u3042\u308b\u305f\u3081\u3001\\(0\u2266\\displaystyle\\frac{5\u03b8}{2}\u2266\\displaystyle\\frac{5\u03c0}{2}\\)\u3067\u3059\u3002\u3053\u306e\u7bc4\u56f2\u3067\\(sin\\displaystyle\\frac{5\u03b8}{2}=0\\)\u3068\u306a\u308b\u306e\u306f\u3001\\(\\displaystyle\\frac{5\u03b8}{2}=0,\u03c0,2\u03c0\\)\u306e\u3068\u304d\u3067\u3059\u3002\u3064\u307e\u308a\u3001\\(\u03b8=0,\\displaystyle\\frac{2\u03c0}{5},\\displaystyle\\frac{4\u03c0}{5}\\)\u3067\u3059\u3002<\/p>\n<p><strong>\u30fb3\u500d\u89d2\u306e\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b<\/strong><\/p>\n<p>\u6b21\u306b\u3001\\(cos\\displaystyle\\frac{3\u03b8}{2}+cos\\displaystyle\\frac{\u03b8}{2}=0\\)\u3092\u89e3\u304d\u307e\u3057\u3087\u3046\u30023\u500d\u89d2\u306e\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u3068\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u5909\u63db\u3067\u304d\u307e\u3059\u3002<\/p>\n<ul>\n<li>\\(cos\\displaystyle\\frac{3\u03b8}{2}=4cos^3\\displaystyle\\frac{\u03b8}{2}-3cos\\displaystyle\\frac{\u03b8}{2}\\)<\/li>\n<\/ul>\n<p>\u305d\u3053\u3067\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\\(cos\\displaystyle\\frac{3\u03b8}{2}+cos\\displaystyle\\frac{\u03b8}{2}=0\\)<\/p>\n<p>\\(4cos^3\\displaystyle\\frac{\u03b8}{2}-3cos\\displaystyle\\frac{\u03b8}{2}+cos\\displaystyle\\frac{\u03b8}{2}=0\\)<\/p>\n<p>\\(4cos^3\\displaystyle\\frac{\u03b8}{2}-2cos\\displaystyle\\frac{\u03b8}{2}=0\\)<\/p>\n<p>\\(cos\\displaystyle\\frac{\u03b8}{2}\\left(2cos^2\\displaystyle\\frac{\u03b8}{2}-1\\right)=0\\)<\/p>\n<p>\\(cos\\displaystyle\\frac{\u03b8}{2}\\left(\\sqrt{2}cos\\displaystyle\\frac{\u03b8}{2}+1\\right)\\)\\(\\left(\\sqrt{2}cos\\displaystyle\\frac{\u03b8}{2}-1\\right)\\)\\(=0\\)<\/p>\n<p>\\(cos\\displaystyle\\frac{\u03b8}{2}=0,\u00b1\\displaystyle\\frac{1}{\\sqrt{2}}\\)<\/p>\n<p>\\(0\u2266\u03b8\u2266\u03c0\\)\u3067\u3042\u308b\u305f\u3081\u3001\\(0\u2266\\displaystyle\\frac{\u03b8}{2}\u2266\\displaystyle\\frac{\u03c0}{2}\\)\u3067\u3059\u3002\u3053\u306e\u7bc4\u56f2\u3067\\(cos\\displaystyle\\frac{\u03b8}{2}=0,\u00b1\\displaystyle\\frac{1}{\\sqrt{2}}\\)\u3068\u306a\u308b\u306e\u306f\u3001\\(\\displaystyle\\frac{\u03b8}{2}=\\displaystyle\\frac{\u03c0}{4},\\displaystyle\\frac{\u03c0}{2}\\)\u306e\u3068\u304d\u3067\u3059\u3002\u3064\u307e\u308a\u3001\\(\u03b8=\\displaystyle\\frac{\u03c0}{2},\u03c0\\)\u3067\u3059\u3002<\/p>\n<p>\u3059\u3079\u3066\u306e\u7d50\u679c\u3092\u5408\u308f\u305b\u308b\u3068\u3001\\(\u03b8=0,\\displaystyle\\frac{2\u03c0}{5},\\displaystyle\\frac{\u03c0}{2},\\displaystyle\\frac{4\u03c0}{5},\u03c0\\)\u304c\u7b54\u3048\u3067\u3059\u3002\u3053\u3046\u3057\u3066\u3001\u7b54\u3048\u3092\u5f97\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n<h2>\u4e09\u89d2\u95a2\u6570\u3067\u8db3\u3057\u7b97\u3092\u304b\u3051\u7b97\u306b\u3001\u304b\u3051\u7b97\u3092\u8db3\u3057\u7b97\u306b\u5909\u3048\u308b<\/h2>\n<p>\u8907\u96d1\u306a\u516c\u5f0f\u306e\u4e00\u3064\u304c\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3067\u3059\u3002\u8db3\u3057\u7b97\u3092\u304b\u3051\u7b97\u306b\u5909\u3048\u305f\u308a\u3001\u304b\u3051\u7b97\u3092\u8db3\u3057\u7b97\u306b\u5909\u3048\u305f\u308a\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u8907\u96d1\u306a\u516c\u5f0f\u3067\u3042\u308b\u305f\u3081\u3001\u899a\u3048\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u52a0\u6cd5\u5b9a\u7406\u3092\u5229\u7528\u3057\u3066\u516c\u5f0f\u3092\u4f5c\u308c\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\u4e09\u89d2\u95a2\u6570\u3067\u8db3\u3057\u7b97\u3084\u304b\u3051\u7b97\u3092\u3059\u308b\u3068\u304d\u3001\u516c\u5f0f\u3092\u5229\u7528\u3067\u304d\u306a\u3044\u304b\u3069\u3046\u304b\u3092\u8003\u3048\u307e\u3057\u3087\u3046\u30022\u500d\u89d2\u30843\u500d\u89d2\u304c\u5b58\u5728\u3057\u3066\u3082\u3001\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u306b\u3088\u3063\u3066\u89e3\u3051\u308b\u554f\u984c\u306f\u591a\u3044\u3067\u3059\u3002<\/p>\n<p>\u4e09\u89d2\u95a2\u6570\u3067\u306f\u52a0\u6cd5\u5b9a\u7406\u306b\u52a0\u3048\u3066\u30012\u500d\u89d2\u306e\u516c\u5f0f\u30843\u500d\u89d2\u306e\u516c\u5f0f\u3001\u534a\u89d2\u306e\u516c\u5f0f\u3001\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u3089\u3092\u3059\u3079\u3066\u4f7f\u3044\u3053\u306a\u305b\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u8a08\u7b97\u5185\u5bb9\u306f\u8907\u96d1\u3067\u3042\u308a\u3001\u8a08\u7b97\u554f\u984c\u3092\u89e3\u304f\u306e\u306f\u96e3\u3057\u3044\u3067\u3059\u3002\u305f\u3060\u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u4f7f\u3044\u3053\u306a\u305b\u308b\u3088\u3046\u306b\u306a\u308c\u3070\u3001\u4e09\u89d2\u95a2\u6570\u306e\u8a08\u7b97\u306f\u5f97\u610f\u3068\u3044\u3048\u307e\u3059\u3002\u305d\u3053\u3067\u516c\u5f0f\u3092\u4f5c\u308c\u308b\u3088\u3046\u306b\u306a\u308a\u3001\u516c\u5f0f\u3092\u5229\u7528\u3057\u3066\u8a08\u7b97\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u3087\u3046\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e09\u89d2\u95a2\u6570\u3067\u306f\u3001\u548c\u3068\u7a4d\u3092\u5909\u63db\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u8db3\u3057\u7b97\u3092\u304b\u3051\u7b97\u306b\u5909\u3048\u305f\u308a\u3001\u304b\u3051\u7b97\u3092\u8db3\u3057\u7b97\u306b\u5909\u3048\u305f\u308a\u3067\u304d\u308b\u306e\u3067\u3059\u3002\u516c\u5f0f\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u306b\u3088\u308a\u3001\u5f0f\u3092\u5909\u5f62\u3067\u304d\u307e\u3059\u3002 \u4e09\u89d2\u95a2\u6570\u306e\u548c\u3068\u7a4d\u306e\u516c\u5f0f\u3092\u899a\u3048\u3066\u306f\u3044\u3051\u307e\u305b\u3093\u3002\u52a0\u6cd5\u5b9a\u7406\u3092\u5229\u7528\u3059\u308b\u3053 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":11417,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[],"class_list":{"0":"post-11410","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-h-math"},"_links":{"self":[{"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/posts\/11410","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/comments?post=11410"}],"version-history":[{"count":15,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/posts\/11410\/revisions"}],"predecessor-version":[{"id":12772,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/posts\/11410\/revisions\/12772"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/media\/11417"}],"wp:attachment":[{"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/media?parent=11410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/categories?post=11410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hatsudy.com\/jp\/wp-json\/wp\/v2\/tags?post=11410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}