{"id":4618,"date":"2025-11-08T22:30:08","date_gmt":"2025-11-08T14:30:08","guid":{"rendered":"http:\/\/jhwk.online\/?p=4618"},"modified":"2025-11-08T22:54:16","modified_gmt":"2025-11-08T14:54:16","slug":"%e5%87%bd%e6%95%b0%e5%af%bc%e6%95%b03%e8%ae%b2%e8%a7%a3-3-2-2","status":"publish","type":"post","link":"http:\/\/jhwk.online\/?p=4618","title":{"rendered":"\u4e09\u89d2\u51fd\u65703-1"},"content":{"rendered":"\n<div class=\"wp-block-stackable-subtitle stk-block-subtitle stk-block stk-8afe3d6\" data-block-id=\"8afe3d6\"><style>.stk-8afe3d6 .stk-block-subtitle__text{font-size:var(--stk--preset--font-size--medium, 20px) !important;color:#0693e3 !important;}@media screen and (max-width:999px){.stk-8afe3d6 .stk-block-subtitle__text{font-size:var(--stk--preset--font-size--medium, 20px) !important;}}<\/style><p class=\"stk-block-subtitle__text stk-subtitle has-text-color\">\u672c\u9898\u75312023\u7ea722\u73ed\u8303\u81f3\u6770\u8bb2\u89e3\uff01<\/p><\/div>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"734\" style=\"aspect-ratio: 1306 \/ 734;\" width=\"1306\" controls src=\"http:\/\/jhwk.online\/wp-content\/uploads\/2025\/11\/\u4e09\u89d2\u51fd\u65703-1.mp4\"><\/video><\/figure>\n\n\n\n<p>[ratemypost]<\/p>\n\n\n\n<hr class=\"wp-block-separator has-text-color has-vivid-cyan-blue-color has-alpha-channel-opacity has-vivid-cyan-blue-background-color has-background is-style-wide\"\/>\n\n\n\n<h5 class=\"wp-block-heading has-vivid-cyan-blue-color has-text-color has-link-color wp-elements-8a052dbd5caa870510f1e594e9e095cf\">\u9898\u76ee\u5c55\u793a\u2014\u2014\u5148\u63a2\u7a76\u3001\u518d\u542c\u8bb2<\/h5>\n\n\n\n\n$\u25b3ABC$\u7684\u5185\u89d2$A\u3001B\u3001C$\u7684\u5bf9\u8fb9\u5206\u522b\u4e3a$a\uff0cb\uff0cc\uff0c$\u5df2\u77e5$(c &#8211; 2b)\\cos A + \\displaystyle \\frac{a^2 + b^2 &#8211; c^2}{2b} = 0$<p>\n\uff081\uff09\u82e5$a = 4$\uff0c$b + c = 8$\uff0c\u6c42$\u25b3ABC$\u7684\u9762\u79ef\uff1b<p>\n\uff082\uff09\u82e5\u89d2$C$\u4e3a\u949d\u89d2\uff0c\u6c42$\\displaystyle \\frac{c}{b}$\u7684\u53d6\u503c\u8303\u56f4.\n\n\n\n<h4 class=\"wp-block-heading has-text-align-center has-text-color has-background has-link-color has-medium-font-size wp-elements-58b20738b8080c684d5fff23cf040d12\" style=\"color:#1e4b69;background:linear-gradient(0deg,rgb(230,242,255) 0%,rgb(230,242,255) 16%,rgb(92,175,230) 100%)\">\u89e3\u9898\u63a2\u7a76\u2014\u2014\u70b9\u51fb\u76f4\u8fbe<\/h4>\n\n\n\n<style>\n  .video-jump-btn {\n    cursor: pointer;\n    text-align: left;\n    background-color: #e6f2ff; \/* \u6de1\u84dd\u8272\u80cc\u666f *\/\n    border: none;\n    padding: 8px 12px;\n    border-radius: 4px;\n    transition: all 0.3s ease; \/* \u5e73\u6ed1\u8fc7\u6e21\u52a8\u753b *\/\n    font-size: 16px;\n  }\n  \n  .video-jump-btn:hover {\n    background-color: #cce0ff; \/* \u7565\u6df1\u7684\u84dd\u8272\u80cc\u666f *\/\n    transform: scale(1.02); \/* \u8f7b\u5fae\u653e\u5927\u6548\u679c *\/\n    box-shadow: 0 2px 4px rgba(0,0,0,0.1); \/* \u589e\u52a0\u8f7b\u5fae\u9634\u5f71 *\/\n  }\n<\/style>\n\n<button class=\"video-jump-btn\" onclick=\"document.querySelector('video').currentTime = 0; document.querySelector('video').play();\">\n\u95ee\u9898\uff081\uff09\u7b2c\u4e00\u6b65\uff1a\u4ecb\u7ecd\u4e09\u89d2\u5f62\u5c04\u5f71\u5b9a\u7406\uff1b\n<\/button>\n\n\n\n<br>\n\n<style>\n  .video-jump-btn {\n    cursor: pointer;\n    text-align: left; \/* \u5de6\u5bf9\u9f50\u6587\u672c *\/\n   \n  }\n<\/style>\n\n<button class=\"video-jump-btn\" onclick=\"document.querySelector('video').currentTime = 33; document.querySelector('video').play();\">\n    \u7b2c\u4e8c\u6b65\uff1a\u4e09\u89d2\u5f62$ABC$\u7684\u9762\u79ef\u4e3a$2\\sqrt{3}$\u3002\n\n<\/button>\n\n\n\n<br>\n<style>\n  .video-jump-btn {\n    cursor: pointer;\n    text-align: left; \/* \u5de6\u5bf9\u9f50\u6587\u672c *\/\n   \n  }\n<\/style>\n\n<button class=\"video-jump-btn\" onclick=\"document.querySelector('video').currentTime =177; document.querySelector('video').play();\">\n\n\u95ee\u9898\uff082\uff09\u7b2c\u4e00\u6b65\uff1a$\\displaystyle\\frac{c}{b}=\\displaystyle\\frac{\\sqrt{3}}{2}\\displaystyle \\frac{1}{\\tan B}$+$\\displaystyle\\frac{1}{2}$\n\n<\/button>\n\n\n\n<br>\n<style>\n  .video-jump-btn {\n    cursor: pointer;\n    text-align: left; \/* \u5de6\u5bf9\u9f50\u6587\u672c *\/\n   \n  }\n<\/style>\n\n<button class=\"video-jump-btn\" onclick=\"document.querySelector('video').currentTime =283; document.querySelector('video').play();\">\n\n\u7b2c\u4e8c\u6b65\uff1a$\\displaystyle \\frac{c}{b}$\u7684\u53d6\u503c\u8303\u56f4\u4e3a$(2,+\\infty)$\n\n<\/button>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>\u7b54\u6848\u89e3\u6790<\/summary>\n \n\n\n\n<p>\uff081\uff09\u7531\u5df2\u77e5\u5f97\\((c &#8211; 2b)\\cos A + a\\cos C = 0\\)\uff0c\u7ed3\u5408\u6b63\u5f26\u5b9a\u7406\u3001\u548c\u89d2\u516c\u5f0f\uff0c\u5f97\\(\\cos A =\\displaystyle \\frac{1}{2}\\)\uff0c\\(A =\\displaystyle \\frac{\\pi}{3}\\)\u3002<\/p>\n<p>\u7531\u4f59\u5f26\u5b9a\u7406\\(\\cos A =\\displaystyle \\frac{b^2 + c^2 &#8211; a^2}{2bc} =\\displaystyle \\frac{1}{2}\\)\uff0c\u5373\\(b^2 + c^2 &#8211; a^2 = bc\\)\u3002<\/p>\n<p>\u4ee3\u5165\\(a = 4\\)\uff0c\\(b + c = 8\\)\uff0c\u5f97\\((b + c)^2 &#8211; a^2 = 3bc\\)\uff0c\u5373\\(64 &#8211; 16 = 3bc\\)\uff0c\\(bc = 16\\)\u3002<\/p>\n<p>\\(S_{\\triangle ABC} =\\displaystyle \\frac{1}{2}bc\\sin A =\\displaystyle \\frac{1}{2}\u00d716\u00d7\\displaystyle\\frac{\\sqrt{3}}{2} = 4\\sqrt{3}\\)\u3002<\/p>\n\n<p>\uff082\uff09\u7531\u6b63\u5f26\u5b9a\u7406\\(\\displaystyle\\frac{c}{b} =\\displaystyle \\frac{\\sin C}{\\sin B}\\)\uff0c\u56e0\\(A =\\displaystyle \\frac{\\pi}{3}\\)\uff0c\u6545\\(B + C =\\displaystyle \\frac{2\\pi}{3}\\)\uff0c\\(C =\\displaystyle \\frac{2\\pi}{3} &#8211; B\\)\u3002<\/p>\n<p>\u89d2\\(C\\)\u4e3a\u949d\u89d2\uff0c\u5f97\\(B \\in (0,\\displaystyle \\frac{\\pi}{6})\\)\u3002<\/p>\n<p>\\(\\displaystyle\\frac{\\sin C}{\\sin B} =\\displaystyle \\frac{\\sin(\\displaystyle \\frac{2\\pi}{3} &#8211; B)}{\\sin B} =\\displaystyle \\frac{\\sqrt{3}}{2} \\cdot\\displaystyle \\frac{1}{\\tan B} +\\displaystyle \\frac{1}{2}\\)\u3002<\/p>\n<p>\u7531\\(B \\in (0,\\displaystyle \\frac{\\pi}{6})\\)\uff0c\\(\\tan B \\in (0,\\displaystyle \\frac{\\sqrt{3}}{3})\\)\uff0c\\(\\displaystyle\\frac{1}{\\tan B} \\in (\\sqrt{3}, +\\infty)\\)\uff0c\u6545\\(\\displaystyle\\frac{c}{b} \\in (2, +\\infty)\\)\u3002<\/p>\n<\/details>\n","protected":false},"excerpt":{"rendered":"<p>\u672c\u9898\u75312023\u7ea722\u73ed\u8303\u81f3\u6770\u8bb2\u89e3\uff01 [ratemypost] \u9898\u76ee\u5c55\u793a\u2014\u2014\u5148\u63a2\u7a76\u3001\u518d\u542c\u8bb2 $\u25b3ABC$\u7684\u5185\u89d2$ [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-4618","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"blocksy_meta":[],"_links":{"self":[{"href":"http:\/\/jhwk.online\/index.php?rest_route=\/wp\/v2\/posts\/4618","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/jhwk.online\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/jhwk.online\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/jhwk.online\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/jhwk.online\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4618"}],"version-history":[{"count":13,"href":"http:\/\/jhwk.online\/index.php?rest_route=\/wp\/v2\/posts\/4618\/revisions"}],"predecessor-version":[{"id":4687,"href":"http:\/\/jhwk.online\/index.php?rest_route=\/wp\/v2\/posts\/4618\/revisions\/4687"}],"wp:attachment":[{"href":"http:\/\/jhwk.online\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4618"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/jhwk.online\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4618"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/jhwk.online\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4618"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}