Geometry yog ib ceg tseem ceeb ntawm kev ua lej. Nws kawm txog spatial zog ntawm cov duab. Ib tug ntawm lawv yog polyhedron hu ua prism. Kab lus no tau mob siab rau teb cov lus nug, dab tsi yog prism thiab cov qauv siv los xam nws cov khoom tseem ceeb.
Polyhedron - prism
Cia peb pib tsab xov xwm tam sim nrog cov lus teb rau lo lus nug, dab tsi yog prism. Nws yog to taub raws li ib tug peb-dimensional polyhedron, uas muaj ob polygonal thiab parallel bases thiab ob peb parallelograms los yog duab plaub. Kom nkag siab zoo dua cov chav kawm ntawm cov duab peb tab tom tham txog, hauv qab no yog ib qho piv txwv ntawm pentagonal prism.
Raws li koj tuaj yeem pom, ob lub pentagons pw hauv cov dav hlau sib npaug thiab sib npaug. Lawv sab yog txuas nrog tsib lub duab plaub, hauv qhov no. Los ntawm qhov piv txwv no nws ua raws li yog tias lub hauv paus ntawm daim duab yog polygon nrog n sab, ces tus naj npawb ntawm vertices ntawm lub prism yog 2n, tus naj npawb ntawm nws lub ntsej muag yuav yog n + 2, thiab tus naj npawb ntawm cov npoo yuav. ua 3n. Nws yog ib qho yooj yim los qhia qhov ntawdQhov ntau ntawm cov ntsiab lus no ua rau Euler's theorem:
3n=2n + n + 2 - 2.
Saum toj no, thaum cov lus teb tau muab rau cov lus nug ntawm qhov prism yog dab tsi, peb tau hais tias lub ntsej muag txuas rau tib lub hauv paus tuaj yeem yog parallelograms lossis duab plaub. Nco ntsoov tias tom kawg yog rau cov chav kawm ntawm tus qub. Tsis tas li ntawd, nws muaj peev xwm hais tias cov ntsej muag no yuav yog squares. Cov sab uas txuas lub hauv paus ntawm lub prism yog hu ua lateral. Lawv tus lej yog txiav txim los ntawm tus naj npawb ntawm cov ces kaum lossis ob sab ntawm lub hauv paus polyhedral.
Qhia luv luv hais tias lub ntsiab lus ntawm lo lus "prism" los ntawm Greek lus, qhov twg nws txhais tau tias "sawed off". Nws yog ib qho yooj yim to taub qhov twg lub npe no los ntawm yog tias koj saib ntawm lub quadrangular ntoo prisms nyob rau hauv daim duab hauv qab no.
Prisms yog dab tsi?
Kev faib tawm ntawm prisms suav nrog kev txiav txim siab ntau yam ntawm cov duab no. Yog li ntawd, ua ntej ntawm tag nrho cov, lub polygonality ntawm lub hauv paus yog coj mus rau hauv tus account, yog li ntawd lawv tham txog triangular, quadrangular thiab lwm yam prisms. Qhov thib ob, cov duab ntawm sab ntsej muag txiav txim siab seb daim duab yog ncaj los yog slanted. Nyob rau hauv daim duab ncaj, tag nrho cov ntsej muag muaj plaub lub kaum sab xis, uas yog, lawv yog cov duab plaub los yog plaub fab. Hauv daim duab inclined, cov ntsej muag no yog parallelograms.
Regular prisms belongs rau qeb tshwj xeeb. Qhov tseeb yog tias lawv cov hauv paus yog sib npaug thiab sib npaug polygons, thiab daim duab nws tus kheej yog ib txoj kab ncaj nraim. Ob tug noqhov tseeb hais tias ob sab ntawm cov duab zoo li txhua tus sib npaug.
Thaum kawg, lwm qhov kev faib tawm yog qhov convexity lossis concavity ntawm lub hauv paus. Piv txwv li, lub concave tsib-taw lub hnub qub yog qhia saum toj no.
qauv rau thaj tsam thiab ntim ntawm daim duab tsis tu ncua
Tau paub tias qhov prism li niaj zaus yog dab tsi, ntawm no yog ob lub ntsiab lus uas koj tuaj yeem txiav txim siab lawv qhov ntim thiab thaj chaw saum npoo.
Vim thaj tsam S ntawm tag nrho daim duab yog tsim los ntawm ob lub hauv paus nrog n sab thiab n duab plaub, cov kab lus hauv qab no yuav tsum tau siv los suav nws:
So=n / 4ctg(pi / n)a2;
S=2So+ na h.
Ntawm So- ib puag yog thaj chaw, ib sab ntawm lub hauv paus, h yog qhov siab ntawm tag nrho daim duab.
txhawm rau xam qhov ntim ntawm hom prism, siv tus qauv:
V=So h=n / 4ctg(pi / n)a2 h.
Kev xam ntawm S thiab V rau cov lej tsis tu ncua yuav tsum muaj kev paub txog tsuas yog ob txoj kab geometric tsis.
Daim duab peb sab iav prism
Dab tsi yog prism, peb xam nws tawm. Qhov no yog ib qho khoom zoo meej ntawm geometry, nws yog siv los muab cov duab rau ntau cov qauv thiab cov khoom. Cia peb nco ntsoov tsuas yog ib qho ntawm cov ntawv thov tseem ceeb ntawm nws daim ntawv hauv physics. Qhov no yog daim duab peb sab prism ua los ntawm iav. Vim nws cov duab, lub teeb ntog rau ntawm nws, raws li ib tug tshwm sim ntawm dispersion, decomposes mus rau hauv ob peb xim, uas tso cai rau koj mus rau dispersion.tshuaj xyuas cov tshuaj muaj pes tsawg leeg ntawm cov emitter.
