Ntawm ntau cov duab geometric, ib qho yooj yim tshaj plaws tuaj yeem hu ua parallelepiped. Nws muaj cov duab ntawm lub prism, nyob rau hauv lub hauv paus ntawm uas yog ib tug parallelogram. Nws tsis yooj yim rau kev xam thaj tsam ntawm lub thawv vim tias cov qauv yooj yim heev.
Ib prism muaj lub ntsej muag, ntsug thiab ntug. Kev faib tawm ntawm cov ntsiab lus no yog tsim los ntawm qhov tsawg kawg nkaus tsim nyog rau kev tsim cov duab geometric. Lub parallelepiped muaj 6 lub ntsej muag, uas txuas nrog 8 vertices thiab 12 npoo. Ntxiv mus, cov opposite sab ntawm parallelepiped yuav ib txwm sib npaug rau ib leeg. Yog li ntawd, txhawm rau txheeb xyuas thaj tsam ntawm parallelepiped, nws txaus los txiav txim siab qhov ntev ntawm nws peb lub ntsej muag.
Lub parallelepiped (Greek rau "parallel edges") muaj qee yam khoom tsim nyog hais txog. Ua ntej, lub symmetry ntawm daim duab yog paub tseeb hais tias tsuas yog nyob rau hauv nruab nrab ntawm txhua ntawm nws diagonals. Thib ob, los ntawm kev kos duab kab pheeb ces kaum ntawm ib qho ntawm cov vertices opposite, koj tuaj yeem pom tias txhua qhov vertices muaj ib qho taw tes.kev sib tshuam. Nws tseem tsim nyog sau cia cov cuab yeej uas cov ntsej muag sib txawv ib txwm sib npaug thiab yuav tsum ua tib zoo sib luag.
Nyob rau hauv qhov xwm txheej, cov hom parallelepipeds no txawv:
- rectangular - muaj plaub lub ntsej muag;
- ncaj - tsuas muaj plaub sab ntsej muag;
- ib qho inclined parallelepiped muaj sab ntsej muag uas tsis yog perpendicular rau hauv paus;
- cube - muaj lub ntsej muag zoo li square.
Cia li sim nrhiav thaj tsam ntawm ib qho parallelepiped siv cov duab plaub ntawm daim duab no ua piv txwv. Raws li peb twb paub lawm, tag nrho nws lub ntsej muag yog duab plaub. Thiab txij li tus naj npawb ntawm cov ntsiab lus no raug txo mus rau rau, tom qab ntawd, tau kawm txog thaj tsam ntawm lub ntsej muag ntawm ntug dej hiav txwv, nws yog qhov yuav tsum tau sau cov txiaj ntsig tau los ua ib tus lej. Thiab mus nrhiav thaj chaw ntawm lawv txhua tus tsis yog qhov nyuaj. Ua li no, muab ob sab ntawm lub duab plaub.
Ib tus lej lej yog siv los txiav txim siab thaj tsam ntawm lub cuboid. Nws muaj cov cim cim qhia txog lub ntsej muag, thaj chaw, thiab zoo li qhov no: S=2 (ab + bc + ac), qhov twg S yog thaj tsam ntawm daim duab, a, b yog ob sab ntawm lub hauv paus, c yog qhov sab ntug.
Cia li muab piv txwv suav. Wb hais a \u003d 20 cm, b \u003d 16 cm, c \u003d 10 cm. Tam sim no koj yuav tsum tau muab cov lej sib npaug raws li cov cai ntawm cov qauv: 2016 + 1610 + 2010 thiab peb tau txais ua 680cm2. Tab sis qhov no yuav tsuas yog ib nrab ntawm daim duab, txij li peb tau kawm thiab sau cov ntsiab lus ntawm peb lub ntsej muag. Vim tias txhua tus ntug muajnws "ob npaug", koj yuav tsum tau muab ob npaug rau qhov txiaj ntsig, thiab peb tau txais thaj tsam ntawm parallelepiped, sib npaug rau 1360 cm2.
txhawm rau xam thaj chaw sab nraud, siv cov qauv S=2c(a + b). Qhov chaw ntawm lub hauv paus ntawm parallelepiped tuaj yeem pom los ntawm kev muab qhov ntev ntawm ob sab ntawm lub hauv paus los ntawm ib leeg.
Nyob rau hauv lub neej txhua hnub, parallelepipeds feem ntau tuaj yeem pom. Peb nco txog lawv lub neej los ntawm cov duab ntawm ib lub cib, lub thawv ntoo, los yog ib qho matchbox zoo tib yam. Piv txwv tuaj yeem pom muaj ntau nyob ib puag ncig peb. Hauv tsev kawm ntawv cov ntaub ntawv qhia txog geometry, ntau zaj lus qhia tau mob siab rau txoj kev kawm ntawm parallelepiped. Thawj ntawm lawv ua qauv qhia txog cov duab plaub parallelepiped. Tom qab ntawd cov tub ntxhais kawm tau qhia yuav ua li cas sau ib lub pob lossis pyramid, lwm cov duab rau hauv nws, nrhiav thaj tsam ntawm parallelepiped. Hauv ib lo lus, qhov no yog daim duab peb sab uas yooj yim tshaj plaws.
