{"id":1766,"date":"2020-08-22T03:03:41","date_gmt":"2020-08-22T02:03:41","guid":{"rendered":"http:\/\/xmau.com\/wp\/ilpost\/?p=1766"},"modified":"2020-08-10T21:28:37","modified_gmt":"2020-08-10T20:28:37","slug":"risposte-ai-problemini-per-ferragosto-2020","status":"publish","type":"post","link":"https:\/\/xmau.com\/ilpost\/2020\/08\/22\/risposte-ai-problemini-per-ferragosto-2020\/","title":{"rendered":"Risposte ai problemini per Ferragosto 2020"},"content":{"rendered":"<p>Per chi era in ambasce, ecco le risposte ai problemini della scorsa settimana!<\/p>\n<p><b><big>1. Triangolate il triangolo<\/big><\/b><br \/>\nPotete vedere la soluzione nella figura qui sotto.<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"1768\" data-permalink=\"https:\/\/xmau.com\/ilpost\/2020\/08\/22\/risposte-ai-problemini-per-ferragosto-2020\/t471a\/\" data-orig-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t471a.png?fit=589%2C533&amp;ssl=1\" data-orig-size=\"589,533\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"t471a\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t471a.png?fit=589%2C533&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2020\/08\/t471a.png?resize=589%2C533\" alt=\"cinque segmenti da ciascun vertice\" width=\"589\" height=\"533\" class=\"aligncenter size-full wp-image-1768\" srcset=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t471a.png?w=589&amp;ssl=1 589w, https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t471a.png?resize=300%2C271&amp;ssl=1 300w\" sizes=\"auto, (max-width: 589px) 100vw, 589px\" \/><br \/>\n<!-- Le suddivisioni con 3, 7 e 19 triangoli corrispondono ai solidi platonici con facce triangolari, dove una delle facce viene bucata in modo da permettere di schiacciare sul piano tutta la figura. Ecco il perch\u00e9 dell'unicit\u00e0 delle soluzioni. --><\/p>\n<p><b><big>2. Triangoli separati<\/big><\/b><br \/>\nPoich\u00e9 c&#8217;\u00e8 solo un numero finito di segmenti possibile che uniscono due dei punti assegnati, \u00e8 possibile trovare una retta che non sia parallela a nessuno di questi segmenti. Consideriamo ora il fascio di rette parallele a questa retta, prendiamone una che lasci tutti i punti da una parte, e cominciamo a spostarla &#8211; sempre rimanendo nel fascio &#8211; verso i punti. Per costruzione verr\u00e0 sempre toccato un punto per volta; a ogni multiplo di tre punti toccati, prendiamo gli ultimi tre e costruiamo il relativo triangolo.<br \/>\n<!-- Finito e infinito sono due concetti diversissimi! --><\/p>\n<p><b><big>3. Pi\u00f9 o meno<\/big><\/b><br \/>\nS\u00ec, \u00e8 possibile. A meno di rotazioni, le uniche due possibilit\u00e0 per un singolo triangolo sono quella con tutti + (che per\u00f2 porta necessariamente a un reticolo con soli +, visto che ci saranno sempre almeno due + per i triangoli adiacenti) e quella indicata in alto nella figura qui sotto. A questo punto una riga del reticolo si completa forzatamente come indicato in basso, e le righe successive si costruiscono per simmetria.<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"1771\" data-permalink=\"https:\/\/xmau.com\/ilpost\/2020\/08\/22\/risposte-ai-problemini-per-ferragosto-2020\/t473a\/\" data-orig-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t473a.png?fit=640%2C340&amp;ssl=1\" data-orig-size=\"640,340\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"t473a\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t473a.png?fit=600%2C319&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2020\/08\/t473a.png?resize=640%2C340\" alt=\"[cominciamo a riempire]\" width=\"640\" height=\"340\" class=\"aligncenter size-full wp-image-1771\" srcset=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t473a.png?w=640&amp;ssl=1 640w, https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t473a.png?resize=300%2C159&amp;ssl=1 300w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" \/><br \/>\n<!-- Questo \u00e8 un problema dove si fa pi\u00f9 in fretta a provare a costruire la soluzione che a pensarci su --><\/p>\n<p><b><big>4. Reticolato<\/big><\/b><br \/>\nNo, non \u00e8 possibile. Se lo fosse, infatti, deve esserci per forza almeno una riga con tre lettere consecutive, come nella figura in alto: altrimenti quella riga avrebbe solo due lettere. Senza perdita di generalit\u00e0, possiamo chiamare le lettere <i>a<\/i>, <i>b<\/i>, <i>c<\/i>. Sotto la <i>b<\/i> deve per forza esserci una <i>d<\/i>, e quindi ai lati della <i>d<\/i> ci devono rispettivamente essere  <i>c<\/i> e <i>a<\/i> (figura di mezzo). Ma allora la riga ancora sotto deve di nuovo avere <i>a<\/i>, <i>b<\/i>, <i>c<\/i> e cos\u00ec via: quindi le colonne hanno solo due lettere e non quattro.<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"1773\" data-permalink=\"https:\/\/xmau.com\/ilpost\/2020\/08\/22\/risposte-ai-problemini-per-ferragosto-2020\/t474a\/\" data-orig-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t474a.png?fit=202%2C362&amp;ssl=1\" data-orig-size=\"202,362\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"t474a\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t474a.png?fit=202%2C362&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2020\/08\/t474a.png?resize=202%2C362\" alt=\"[ i passi della risposta]\" width=\"202\" height=\"362\" class=\"aligncenter size-full wp-image-1773\" srcset=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t474a.png?w=202&amp;ssl=1 202w, https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t474a.png?resize=167%2C300&amp;ssl=1 167w\" sizes=\"auto, (max-width: 202px) 100vw, 202px\" \/><br \/>\n<!-- In un certo senso, questa \u00e8 una tipica dimostrazione per colorazione appropriata. --><\/p>\n<p><b><big>5. Sviluppare il cubo<\/big><\/b><br \/>\nL&#8217;unica soluzione possibile \u00e8 mostrata qui sotto. Piegare per credere!<br \/>\n<img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"1777\" data-permalink=\"https:\/\/xmau.com\/ilpost\/2020\/08\/22\/risposte-ai-problemini-per-ferragosto-2020\/t475a\/\" data-orig-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t475a.png?fit=402%2C302&amp;ssl=1\" data-orig-size=\"402,302\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"t475a\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t475a.png?fit=402%2C302&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2020\/08\/t475a.png?resize=402%2C302\" alt=\"[un altro sviluppo del cubo]\" width=\"402\" height=\"302\" class=\"aligncenter size-full wp-image-1777\" srcset=\"https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t475a.png?w=402&amp;ssl=1 402w, https:\/\/i0.wp.com\/xmau.com\/ilpost\/wp-content\/uploads\/sites\/5\/2020\/08\/t475a.png?resize=300%2C225&amp;ssl=1 300w\" sizes=\"auto, (max-width: 402px) 100vw, 402px\" \/><br \/>\n<!-- per i curiosi, gli sviluppi essenzialmente diversi del cubo sono 11. In sei di essi ci sono quattro quadrati allineati, in quattro ce ne sono tre, e l'ultimo \u00e8 quello qui mostrato. --><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Per chi era in ambasce, ecco le risposte ai problemini della scorsa settimana! 1. Triangolate il triangolo Potete vedere la [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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ai problemini per Ferragosto 2019","author":".mau.","date":"22\/08\/2019","format":false,"excerpt":"Come vedete, i problemi non erano poi cos\u00ec difficili...","rel":"","context":"In \"quizzini\"","block_context":{"text":"quizzini","link":"https:\/\/xmau.com\/ilpost\/tag\/quizzini\/"},"img":{"alt_text":"indicati gli angoli","src":"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2019\/08\/t401a.png?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2019\/08\/t401a.png?resize=350%2C200 1x, https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2019\/08\/t401a.png?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2019\/08\/t401a.png?resize=700%2C400 2x, https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2019\/08\/t401a.png?resize=1050%2C600 3x, 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semplici del solito","rel":"","context":"In \"quizzini\"","block_context":{"text":"quizzini","link":"https:\/\/xmau.com\/ilpost\/tag\/quizzini\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/xmau.com\/wp\/ilpost\/wp-content\/uploads\/sites\/4\/2019\/04\/q381a.png?resize=350%2C200","width":350,"height":200},"classes":[]}],"_links":{"self":[{"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/posts\/1766","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/comments?post=1766"}],"version-history":[{"count":5,"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/posts\/1766\/revisions"}],"predecessor-version":[{"id":1782,"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/posts\/1766\/revisions\/1782"}],"wp:attachment":[{"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/media?parent=1766"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/categories?post=1766"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xmau.com\/ilpost\/wp-json\/wp\/v2\/tags?post=1766"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}