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[shilokko]
Joined: 02 Nov 2003 Posts: 566 Location: zagreb-vela luka
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Posted: 24.06.2004 01:06 Post subject: Matematicari, pliz! |
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ako moze tko rijesit (rec mi kako rijesit)
Quote: | Katete pravokutnog trokuta iznose 8 i 15. Kružnica prolazi polovištima stranica. Polumjer kružnice je:
1) 7/2 2) 17/4 3) 17/2 4) 2 5) 3
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I je li zna tko formulu za radijus upisane kugle u stožac?
veri
tnku |
_________________ A wise man speaks because he has something to say, a fool because he has to say something. |
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spilja
Joined: 12 Mar 2004 Posts: 743
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Posted: 24.06.2004 09:59 Post subject: |
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eh, sad sam u knjiznici pa mi je nezgodno rjesit ti prvi zadatak.
a ovo sa stoscem, radi se o presjeku koji je trokut, a u njega je upisana kruznica.
povrsina trokuta je P=r*s, gdje je s=(a+b+c)/2. pis of kejk. |
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ahri
Joined: 04 Nov 2003 Posts: 27 Location: Zagreb
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Posted: 24.06.2004 16:07 Post subject: |
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pitaj filca, mislim da on zna odgovor na zadatak ;) |
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ahri
Joined: 04 Nov 2003 Posts: 27 Location: Zagreb
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Posted: 24.06.2004 16:09 Post subject: |
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btw, a kugla upisana u pravilnu peterostranu piramidu? :) |
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Sulien
Joined: 04 Jan 2004 Posts: 2905 Location: Zagreb
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Posted: 24.06.2004 17:07 Post subject: |
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ahri
Joined: 04 Nov 2003 Posts: 27 Location: Zagreb
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Posted: 24.06.2004 17:24 Post subject: |
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kad vec nabijam postove, molio bih da primjetite kad sam se joinao, a koliki broj postova imam :) |
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Philatz
Joined: 22 Sep 2003 Posts: 3176 Location: Zagreb/Croatia .. London/UK
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[shilokko]
Joined: 02 Nov 2003 Posts: 566 Location: zagreb-vela luka
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Posted: 25.06.2004 11:32 Post subject: |
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a kako? |
_________________ A wise man speaks because he has something to say, a fool because he has to say something. |
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ahri
Joined: 04 Nov 2003 Posts: 27 Location: Zagreb
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Posted: 25.06.2004 12:22 Post subject: |
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lahko odredis da je c = 17, jer je trokut pravokutni.
kad spojis sredista te 3 stranice, dobijes slican trokut prethodnom (dakle, isto ima pravi kut).
stranice su mu, naravno, duplo manje.
(a1=4, b1=15/2, c1= 17/2)
i sad te zanima radijus opisane kruznice tom trokutu.
mozes na nekoliko nacina odredit, jedan je "duljina hipotenuze kroz dva", jer je trokut pravokutan
mozes i odrediti povrsinu, pa onda po formuli P=abc/(4R), sto vrijedi za svaki trokut
heto |
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[shilokko]
Joined: 02 Nov 2003 Posts: 566 Location: zagreb-vela luka
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Posted: 25.06.2004 12:28 Post subject: |
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e hvala |
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ahri
Joined: 04 Nov 2003 Posts: 27 Location: Zagreb
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Posted: 25.06.2004 12:41 Post subject: |
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np, filac mi shapno ;) |
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