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Pojam vektora razvio se iz teorije orijentiranih ili usmjerenih dužina. <span style="color: #000000"><i>Orijentirana dužina</i></span> <span style="text-decoration:overline;"><span style="color: #000000"><i>AB</i></span></span> dužina je <span style="text-decoration:overline;"><span style="color: #000000"><i>AB</i></span></span> kojoj je određena početna <span style="color: #000000"><i>A</i></span> točka i zavr&scaron;na <span style="color: #000000"><i>B</i></span> točka, pa se grafički označuje strelicom od <span style="color: #000000"><i>A</i></span> prema <span style="color: #000000"><i>B</i></span>. Dvije orijentirane dužine <span style="text-decoration:overline;"><span style="color: #000000"><i>AB</i></span></span> i <span style="text-decoration:overline;"><span style="color: #000000"><i>CD</i></span></span> <span style="color: #000000"><i>ekvivalentne</i></span> su ako se jedna iz druge mogu dobiti paralelnim pomakom. Skup svih međusobno ekvivalentnih orijentiranih dužina naziva se <span style="color: #000000"><i>vektor</i></span> (<span style="color: #000000"><i><b>a</b></i></span>), kojemu je svaka od tih orijentiranih dužina <span style="text-decoration:overline;"><span style="color: #000000"><i>AB</i></span></span>, <span style="text-decoration:overline;"><span style="color: #000000"><i>CD</i></span></span>, &hellip; <span style="color: #000000"><i>reprezentant</i></span>.</p><p><span style="color: #000000"><i>Vektorska algebra</i></span> omogućuje algebarski prikaz vektora u trodimenzijskom prostoru i izvođenje algebarskih operacija nad vektorima, <span style="color: #000000"><i>vektorska analiza</i></span> bavi se diferenciranjem i integriranjem <a href="https://www.enciklopedija.hr/clanak/vektorsko-polje">vektorskih</a> i <a href="https://www.enciklopedija.hr/clanak/skalarno-polje">skalarnih polja</a>, tj. primjenom metoda infinitezimalnoga računa na vektore, a <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/linearna-algebra">linearna algebra</a></i></span> proučava vektorske prostore, linearne operatore i sustave linearnih jednadžbi.</p><p><span style="color: #000000"><h2><a name="poglavlje1"></a>Vrste vektora</h2> </b></i></span> <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/jedinicni-vektor">Jedinični vektor</a></i></span> jediničnoga je iznosa, <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/nulvektor">nulvektor</a></i></span> je duljine jednake nuli, <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/radijvektor">radijvektoru</a></i></span> je početak u nekoj nepomičnoj točki, obično u ishodi&scaron;tu nekoga <a href="https://www.enciklopedija.hr/clanak/koordinatni-sustavi">koordinatnog sustava</a>, a zavr&scaron;etak u promatranoj točki. <span style="color: #000000"><i>Kolinearni vektori</i></span> paralelni su s istim pravcem, a <span style="color: #000000"><i>komplanarni vektori</i></span> paralelni su s istom ravninom. Međusobno <span style="color: #000000"><i>suprotni vektori</i></span> jednaki su po duljini i suprotnoga smjera.</p><p><span style="color: #000000"><h2><a name="poglavlje2"></a>Vektorske operacije</h2> </b></i></span> 1) <span style="color: #000000"><i>Zbrajanje</i></span> <span style="color: #000000"><i><b>a</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>c</b></i></span>, gdje je <span style="color: #000000"><i><b>c</b></i></span> vektor određen svojim reprezentantom <span style="text-decoration:overline;"><span style="color: #000000"><i>OC</i></span></span>, koji se dobiva <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/pravilo-paralelograma">pravilom paralelograma</a></i></span> iz reprezentanata <span style="text-decoration:overline;"><span style="color: #000000"><i>OA</i></span></span> i <span style="text-decoration:overline;"><span style="color: #000000"><i>OB</i></span></span> vektora <span style="color: #000000"><i><b>a</b></i></span>, odnosno <span style="color: #000000"><i><b>b</b></i></span> po shemi <span style="text-decoration:overline;"><span style="color: #000000"><i>OA</i></span></span>&nbsp;+&nbsp;<span style="text-decoration:overline;"><span style="color: #000000"><i>OB</i></span></span>&nbsp;=&nbsp;<span style="text-decoration:overline;"><span style="color: #000000"><i>OC</i></span></span>, ili <span style="color: #000000"><i>pravilom trokuta</i></span> po shemi <span style="text-decoration:overline;"><span style="color: #000000"><i>OA</i></span></span>&nbsp;+&nbsp;<span style="text-decoration:overline;"><span style="color: #000000"><i>AC</i></span></span><span style="color: #000000"><i>&nbsp;=&nbsp;</i></span><span style="text-decoration:overline;"><span style="color: #000000"><i>OC</i></span></span>. Zbrajanje je komutativno i asocijativno.</p><p>2) <span style="color: #000000"><i>Umnožak vektora sa skalarom</i></span> (brojem) <span style="color: #000000"><i>t</i></span>, <span style="color: #000000"><i>t<b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>b</b></i></span>, jest vektor <span style="color: #000000"><i><b>b</b></i></span> paralelan s vektorom&nbsp;<span style="color: #000000"><i><b>a</b></i></span> i s njim iste ili suprotne orijentacije već prema tomu je li <span style="color: #000000"><i>t</i></span>&nbsp;&gt;&nbsp;0 ili <span style="color: #000000"><i>t</i></span>&nbsp;&lt;&nbsp;0 dok mu je duljina ili modul |<span style="color: #000000"><i>t<b>a</b></i></span>|&nbsp;=&nbsp;|<span style="color: #000000"><i>t</i></span>|&nbsp;|<span style="color: #000000"><i><b>a</b></i></span>|. Svojstva su ove operacije: (<span style="color: #000000"><i>st</i></span>) <span style="color: #000000"><i><b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>s</i></span> (<span style="color: #000000"><i>t<b>a</b></i></span>); (<span style="color: #000000"><i>s</i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>t</i></span>) <span style="color: #000000"><i><b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>s<b>a</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>t<b>a</b></i></span>; <span style="color: #000000"><i>t</i></span>&nbsp;(<span style="color: #000000"><i><b>a</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>b</b></i></span>)&nbsp;=&nbsp;<span style="color: #000000"><i>t<b>a</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>t<b>b</b></i></span>.</p><p>3) <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/skalarni-umnozak">Skalarni umnožak</a></i></span> <span style="color: #000000"><i><b>a</b></i></span>&nbsp;∙&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;|<span style="color: #000000"><i><b>a</b></i></span>|&nbsp;∙&nbsp;|<span style="color: #000000"><i><b>b</b></i></span>|&nbsp;∙&nbsp;cos&nbsp;<span style="color: #000000"><i>&phi;</i></span> jest skalar, gdje je <span style="color: #000000"><i>&phi;</i></span> kut između vektora <span style="color: #000000"><i><b>a</b></i></span> i <span style="color: #000000"><i><b>b</b></i></span>. Svojstva su mu: <span style="color: #000000"><i>komutativnost <b>a</b></i></span>&nbsp;∙&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;∙&nbsp;<span style="color: #000000"><i><b>a</b></i></span>, distributivnost (<span style="color: #000000"><i><b>a</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>b</b></i></span>)&nbsp;∙&nbsp;<span style="color: #000000"><i><b>c</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>a</b></i></span>&nbsp;∙&nbsp;<span style="color: #000000"><i><b>c</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;∙&nbsp;<span style="color: #000000"><i><b>c</b></i></span> i <span style="color: #000000"><i>t</i></span>(<span style="color: #000000"><i><b>a</b></i></span>&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>)&nbsp;=&nbsp;(<span style="color: #000000"><i>t<b>a</b></i></span>)&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>a</b></i></span>&nbsp;&middot;&nbsp;(<span style="color: #000000"><i>t<b>b</b></i></span>).</p><p>4) <span style="color: #000000"><i><a href="https://www.enciklopedija.hr/clanak/vektorski-umnozak">Vektorski umnožak</a></i></span> <span style="color: #000000"><i><b>a</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>c</b></i></span> jest vektor okomit na <span style="color: #000000"><i><b>a</b></i></span> i <span style="color: #000000"><i><b>b</b></i></span>, koji s njima čini tzv. <span style="color: #000000"><i>desnu trojku</i></span> i vrijedi |<span style="color: #000000"><i><b>a</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>|&nbsp;=&nbsp;|<span style="color: #000000"><i><b>a</b></i></span>|&nbsp;&middot;&nbsp;|<span style="color: #000000"><i><b>b</b></i></span>|&nbsp;&middot;&nbsp;sin&nbsp;<span style="color: #000000"><i>&phi;</i></span>.</p><p>5) Za <span style="color: #000000"><i>mje&scaron;oviti vektorski umnožak</i></span> vrijedi: (<span style="color: #000000"><i><b>a</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>)&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>c</b></i></span>&nbsp;=&nbsp;(<span style="color: #000000"><i><b>b</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>c</b></i></span>)&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>a</b></i></span>&nbsp;=&nbsp;(<span style="color: #000000"><i><b>c</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>a</b></i></span>)&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>.</p><p>6) Za <span style="color: #000000"><i>dvostruki vektorski umnožak</i></span> vrijedi: (<span style="color: #000000"><i><b>a</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>)&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>c</b></i></span>&nbsp;=&nbsp;(<span style="color: #000000"><i><b>a</b></i></span>&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>c</b></i></span>)<span style="color: #000000"><i><b>b</b></i></span>&nbsp;&ndash;&nbsp;(<span style="color: #000000"><i><b>b</b></i></span>&nbsp;&middot;&nbsp;<span style="color: #000000"><i><b>c</b></i></span>)<span style="color: #000000"><i><b>a</b></i></span>.</p><p><span style="color: #000000"><h2><a name="poglavlje3"></a>Prikaz vektora u Kartezijevu koordinatnom sustavu</h2> </b></i></span>U Kartezijevu koordinatnom sustavu vektori se izražavaju s pomoću koordinata i jediničnih vektora <span style="color: #000000"><i><b>i</b></i></span>, <span style="color: #000000"><i><b>j</b></i></span>, <span style="color: #000000"><i><b>k</b></i></span> u smjerovima koordinatnih osi <span style="color: #000000"><i>x</i></span>, <span style="color: #000000"><i>y</i></span> i <span style="color: #000000"><i>z</i></span>. Primjerice, ako je vektorima <span style="color: #000000"><i><b>a</b></i></span> i <span style="color: #000000"><i><b>b</b></i></span> početak u ishodi&scaron;tu koordinatnog sustava a zavr&scaron;etci u točkama <span style="color: #000000"><i>A</i></span>(<span style="color: #000000"><i>a</i></span><sub>x</sub>, <span style="color: #000000"><i>a</i></span><sub>y</sub>, <span style="color: #000000"><i>a</i></span><sub>z</sub>) i <span style="color: #000000"><i>B</i></span>(<span style="color: #000000"><i>b</i></span><sub>x</sub>, <span style="color: #000000"><i>b</i></span><sub>y</sub>, <span style="color: #000000"><i>b</i></span><sub>z</sub>), tada je <span style="color: #000000"><i><b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>a</i></span><sub>x</sub>&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>a</i></span><sub>y</sub>&nbsp;<span style="color: #000000"><i><b>j</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>a</i></span><sub>z</sub>&nbsp;<span style="color: #000000"><i><b>k</b></i></span> i <span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>b</i></span><sub>x</sub>&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b</i></span><sub>y</sub>&nbsp;<span style="color: #000000"><i><b>j</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b</i></span><sub>z</sub>&nbsp;<span style="color: #000000"><i><b>k</b></i></span>.</p><p>Vektorske operacije u Kartezijevu koordinatnom sustavu:</p><p>1) zbrajanje <span style="color: #000000"><i><b>a</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;(<span style="color: #000000"><i>a</i><sub><i>x</i></sub></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b</i><sub><i>x</i></sub></span>)&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;(<span style="color: #000000"><i>a</i><sub><i>y</i></sub></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b</i><sub><i>y</i></sub></span>)<span style="color: #000000"><i>&nbsp;<b>j</b></i></span>&nbsp;+&nbsp;(<span style="color: #000000"><i>a</i><sub><i>z</i></sub></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b</i><sub><i>z</i></sub></span>)&nbsp;<span style="color: #000000"><i><b>k</b></i></span>,</p><p>2) umnožak vektora sa skalarom&nbsp;<span style="color: #000000"><i>t<b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>ta</i><sub><i>x</i></sub></span>&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>ta<sub>y</sub><b>j</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>ta<sub>z</sub><b>k</b></i></span>,</p><p>3) skalarni umnožak <span style="color: #000000"><i><b>a</b></i></span>&nbsp;∙&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i><b>a</b><sub>x</sub> <b>b</b></i><sub><i>x</i></sub></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>a</b><sub>y</sub> <b>b</b></i><sub><i>y</i></sub></span>&nbsp;+&nbsp;<span style="color: #000000"><i><b>a</b><sub>z</sub> <b>b</b></i><sub><i>z</i></sub></span>,</p><p>4) vektorski umnožak <span style="color: #000000"><i><b>a</b></i></span>&nbsp;&times;&nbsp;<span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;(<span style="color: #000000"><i>a</i><sub><i>y</i></sub></span>&nbsp;<span style="color: #000000"><i>b</i><sub><i>z</i></sub></span>&nbsp;&ndash;&nbsp;<span style="color: #000000"><i>a</i><sub><i>z</i></sub></span>&nbsp;<span style="color: #000000"><i>b</i><sub><i>y</i></sub></span>)&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;(<span style="color: #000000"><i>a</i><sub><i>z</i></sub></span>&nbsp;<span style="color: #000000"><i>b</i><sub><i>x</i></sub></span>&nbsp;&ndash;&nbsp;<span style="color: #000000"><i>a</i><sub><i>x</i></sub></span>&nbsp;<span style="color: #000000"><i>b</i><sub><i>z</i></sub></span>)&nbsp;<span style="color: #000000"><i><b>j</b></i></span>&nbsp;+&nbsp;(<span style="color: #000000"><i>a</i><sub><i>x</i></sub></span>&nbsp;<span style="color: #000000"><i>b</i><sub><i>y</i></sub></span>&nbsp;&ndash;&nbsp;<span style="color: #000000"><i>a</i><sub><i>y</i></sub></span>&nbsp;<span style="color: #000000"><i>b</i><sub><i>x</i></sub></span>)&nbsp;<span style="color: #000000"><i><b>k</b></i></span>.</p><p><span style="color: #000000"><i>Duljina vektora</i></span> <span style="color: #000000"><i><b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>a<sub>x</sub></i></span>&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>a<sub>y</sub></i></span>&nbsp;<span style="color: #000000"><i><b>j</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>a</i><sub><i>z</i></sub></span>&nbsp;<span style="color: #000000"><i><b>k</b></i></span> dana je izrazom: \(a=\sqrt{a_x^2+a_y^2+a_z^2}.\)</p><p><span style="color: #000000"><i>Kut</i></span> između vektora <span style="color: #000000"><i><b>a</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>a<sub>x</sub></i></span><span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>a<sub>y</sub></i></span>&nbsp;<span style="color: #000000"><i><b>j</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>a<sub>z</sub></i></span>&nbsp;<span style="color: #000000"><i><b>k</b></i></span> i <span style="color: #000000"><i><b>b</b></i></span>&nbsp;=&nbsp;<span style="color: #000000"><i>b<sub>x</sub></i></span>&nbsp;<span style="color: #000000"><i><b>i</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b<sub>y</sub></i></span>&nbsp;<span style="color: #000000"><i><b>j</b></i></span>&nbsp;+&nbsp;<span style="color: #000000"><i>b<sub>z</sub></i></span>&nbsp;<span style="color: #000000"><i><b>k</b></i></span> može se odrediti iz izraza:</p><p>\[{\rm cos\,\varphi}=\cfrac{\pmb {a\cdot b}}{ab}=\cfrac{a_xb_x+a_yb_y+a_zb_z}{\sqrt{a_x^2+a_y^2+a_z^2}\cdot\sqrt{b_x^2+b_y^2+b_z^2}}.\]</p><p><span style="color: #000080"><b>2.</b></span> U fizici, veličina koja je definirana ako su određeni apsolutni iznos (vrijednost, intenzitet, modul), pravac i smjer duž pravca bez obzira na položaj <a href="https://www.enciklopedija.hr/clanak/hvatiste">hvati&scaron;ta</a> (početne točke vektora). U koordinatnom sustavu vektor je definiran s pomoću svojih projekcija na koordinatne osi. Vektori su npr. sila, brzina, ubrzanje, jakost električnoga polja. Grafički, vektori se prikazuju s pomoću usmjerenih dužina. Za razliku od vektora, veličine definirane samim iznosom, kao masa, energija, temperatura i dr:, nazivaju se <a href="https://www.enciklopedija.hr/clanak/56364">skalari</a>.</p><p><span style="color: #000080"><b>3.</b></span> U biologiji: a) organizam, npr. komarac ili krpelj, koji prenosi mikroorganizme, uzročnike bolesti; b) u <a href="https://www.enciklopedija.hr/clanak/geneticko-inzenjerstvo">genetičkom inženjerstvu</a>, vektori su molekule DNA u koje se mogu ugraditi sintetski ili prirodni geni i potom prenijeti u stanicu domaćina. Kao vektori najče&scaron;će služe <a href="https://www.enciklopedija.hr/clanak/plazmidi">plazmidi</a> i virusne DNA, sposobni za replikaciju u ciljnim stanicama. Kombinacijom plazmida i <a href="https://www.enciklopedija.hr/clanak/bakteriofagi">bakteriofaga</a> dobiveni su <span style="color: #000000"><i>kozmidi,</i></span> vektori prikladni za kloniranje većih isječaka DNA. Klonirani geni u transformiranoj će stanici domaćina proizvoditi bjelančevine za strukturu kojih nose informaciju, pa će toj stanici donijeti svojstva koja prije nije imala. (&rarr;&nbsp;<span style="color: #000000"><span style="font-variant: small-caps"><a href="https://www.enciklopedija.hr/clanak/rekombinantna-dna">rekombinantna dna</a></span></span>)</p> </div> </div> </div> <div class="container citiranje"> Citiranje: <p> vektor. <i>Hrvatska enciklopedija</i>, <i>mrežno izdanje.</i> Leksikografski zavod Miroslav Krleža, 2013. – 2024. 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