txhawm rau daws cov teeb meem ntawm cov ncauj lus dav dav "Stereometry", koj yuav tsum kawm thiab txheeb xyuas ntau lub ntsiab lus thiab cov ntsiab lus, kawm tag nrho cov khoom ntawm cov duab, thiab tsis txhob hnov qab txog cov khoom ntawm txhua daim duab uas suav nrog. hauv chav kawm "Planimetry"
Ntawm cov teeb meem ntawm cov duab peb sab, qhov tseeb pyramid feem ntau pom, txhawm rau daws tau lawv yooj yim, koj yuav tsum paub zoo. Lub pyramid yog hu ua tsis tu ncua yog tias nws muaj ib qho polygon tsis tu ncua ntawm nws lub hauv paus thiab nws cov vertex yog npaj rau hauv nruab nrab ntawm lub hauv paus. Ib yam li koj kawm qhov polygon no, koj yuav hnov txog apothem.
Raws li koj tau nkag siab lawm, hauv geometry lub tswv yim ntawm apothem yog qhov tshwm sim thoob plaws. Nws yog tsis yooj yim sua kom paub tej qhov ntev ntawm lub pyramid yam tsis paub nws. Lo lus "apothem" yog ib qho tshwm sim tuaj rau peb los ntawm cov lus Greek, thiab nws tau txhais tias "Kuv ncua."
Definition
Nyob rau hauv planimetry, apothem yog ib qho perpendicular (ob leeg nws tus kheej thiab nws qhov ntev), uas yog kos rau sab ntawm ib tug niaj hnub polygon ntawm qhov chaw. Hauv stereometriclub apothem ntawm lub pyramid yog qhov siab nyob rau hauv lub ntsej muag sab, uas yog kos rau hauv paus. Tsuas yog siv rau cov pyramids tsis tu ncua. Raws li txoj cai, lub apothem ntawm ib daim duab peb sab tsis tu ncua yog qhov siab ntawm nws lub ntsej muag, uas yog sawv cev los ntawm daim duab peb sab isosceles.
lub luag haujlwm ntawm apothem yog dab tsi
Apothem yog lub ntsiab lus tseem ceeb ntawm lub pyramid, vim nws tuaj yeem siv los daws cov teeb meem loj heev. Hauv particular, sab nraud ntawm lub pyramid tsis tu ncua yog sib npaug rau ib nrab ntawm cov khoom ntawm ib puag ncig ntawm lub hauv paus thiab lub ntsej muag ntawm lub ntsej muag.
Sbp =(Pmainh)/2; h yog apothem, qhov no yog nws lub luag haujlwm tseem ceeb.
Tsis txhob yuam kev H (qhov siab ntawm daim duab peb sab hauv stereometry).
Tseem, ua tsaug rau qhov kev paub ntawm apothem, koj tuaj yeem pom thaj tsam ntawm lub ntsej muag zoo li daim duab peb sab isosceles.
Apothem khoom
Lawv muaj tsawg, tab sis tseem yuav tsum nco ntsoov. Feem ntau, cov no yog qhov tshwm sim tom qab los ntawm kev txhais. Yog li, lub apothem nyob rau hauv qhov tseeb pyramid:
- qis rau sab ntawm lub hauv paus ntawm lub kaum sab xis 90 degree.
- Sib faib sab uas nws qis dua ib nrab, vim nws yog qhov siab hauv ib qho isosceles / equilateral daim duab peb sab thiab, ua ke, qhov nruab nrab.
Nyob hauv lub pyramid li niaj zaus, txhua tus apothems sib npaug, vim tag nrho nws sab ntsej muag kuj zoo ib yam. Thaum pom qhov ntev ntawm lub apothem, koj yuav tsum tau siv ob qho tib si cov khoom ntawm ib tug polygon thiab cov khoom ntawm ib tug polyhedron. Yuav ua li cas thiaj nrhiav tau tus lej ntawm tus apothem hauv lub pyramid kom raug?
Yuav ua li cas thiaj nrhiav tau tus apothem ntawm lub pyramid
Nws tuaj yeem pom los ntawm kev siv txhua qhov kev paub yav dhau los, yog tag nrhotsuas yog qee qhov piv txwv:
- Yog hais tias sab ntug thiab puag sab paub. Txij li thaum lub apothem faib sab ntawm lub hauv paus nyob rau hauv ib nrab thiab tsim ib lub kaum sab xis ntawm 90 degrees nrog nws, nws yuav tsis yooj yim rau koj mus nrhiav tau nws los ntawm ib tug txoj cai daim duab peb sab siv lub Pythagorean theorem. Koj tseem tuaj yeem pom lub apothem siv kev paub txog qhov sib piv hauv daim duab peb sab yog.
- Yog tias koj paub lub vojvoog ntawm lub voj voog inscribed ntawm lub hauv paus ntawm lub pyramid tsis tu ncua thiab qhov siab ntawm tag nrho daim duab. Lub vojvoog rub mus rau qhov taw tes tangent yog perpendicular rau lub tangent, thiab lub apothem yog perpendicular rau sab ntawm lub hauv paus (uas yog tangent rau lub voj voog inscribed). Qhov siab ntawm daim duab yog perpendicular mus rau lub hauv paus thiab ntog rau hauv nruab nrab ntawm lub voj voog inscribed nyob rau hauv lub hauv paus ntawm lub pyramid. Yog li ntawd, lub vojvoog thiab qhov siab ntawm daim duab yog ob txhais ceg thiab tsim lub kaum sab xis, thiab ua ke nrog lub apothem, ib daim duab peb sab. Thiab dua, siv Pythagorean theorem lossis los ntawm qhov sib piv hauv daim duab peb sab, koj tuaj yeem nrhiav tau yooj yim apothem.
Tsi yog muab lub ntsej muag thiab lub hauv paus paub
Txawm li cas los xij, thaum nrhiav lub apothem, koj yuav tsum nco ntsoov tag nrho cov cai thiab cov cai ntawm cov phiaj xwm. Yog tias qee lub ntsiab lus los ntawm cov npe no tsis paub, ces koj tuaj yeem ua haujlwm nrog cov kev txwv no, thiab maj mam nrhiav cov ntaub ntawv saum toj no, nws yuav tsis yooj yim rau koj los nrhiav ib qho apothem. Peb cia siab tias peb tsab xov xwm yuav pab tau koj nyob rau hauv lub tswv yim zoo li no.
