Daim duab peb sab yog daim duab geometric uas muaj peb lub ntsiab lus txuas los ntawm cov kab uas tsis nyob ntawm ib txoj kab ncaj nraim hauv lub dav hlau. Lub vertices ntawm daim duab peb sab yog cov ntsiab lus ntawm lub hauv paus ntawm cov ces kaum, thiab cov kab txuas lawv hu ua ob sab ntawm daim duab peb sab. Txhawm rau txiav txim siab thaj tsam ntawm daim duab, qhov chaw sab hauv ntawm daim duab peb sab feem ntau siv.
Kev faib tawm
Ntxiv rau daim duab peb sab uas tsis sib npaug, muaj cov duab peb sab isosceles, uas yog, muaj ob sab zoo ib yam. Lawv hu ua lateral, thiab lwm sab yog hu ua lub hauv paus ntawm daim duab. Muaj lwm hom polygons - sib npaug. Tag nrho peb sab yog tib qhov ntev.
Daim duab peb sab muaj qhov ntsuas ntsuas ntsuas. Cov duab no tuaj yeem muaj qhov sib txawv, yog li lawv tau faib raws li hauv qab no:
- Rectangular - muaj lub kaum sab xis ntawm 90 degrees. Ob sab uas nyob ib sab ntawm lub kaum sab xis no hu ua ob txhais ceg, thiab qhov thib peb hu ua hypotenuse;
- Daim duab peb sab yog daim duab peb sab uas muaj txhua lub kaum sab xis tsis tshaj 90degrees;
- Obtuse - ib lub kaum sab xis siab dua 90 degrees.
Definition and parameters of ib daim duab peb sab
Raws li twb tau sau tseg lawm, daim duab peb sab yog ib qho ntawm cov hom polygons uas muaj peb lub vertices thiab tib cov kab sib txuas. Cov kab feem ntau yog qhia nyob rau hauv tib txoj kev: cov ces kaum yog nyob rau hauv me me Latin ntawv, thiab cov opposite sab ntawm txhua tus yog nyob rau hauv cov ntaub ntawv capital.
Yog tias koj ntxiv tag nrho cov kaum sab xis ntawm daim duab peb sab, koj tau txais qhov sib npaug ntawm 180 degrees. Txhawm rau kom paub lub kaum sab hauv, koj yuav tsum rho tawm lub kaum sab xis ntawm daim duab peb sab los ntawm 180degrees. Yuav kom paub seb lub kaum sab nraud sib npaug li cas, nws tsim nyog ntxiv ob lub kaum sab hauv sib cais los ntawm nws.
Nyob rau hauv txhua daim duab peb sab, txawm tias nws muaj lub kaum sab xis lossis obtuse, sab loj yog qhov sib txawv rau lub kaum sab xis loj. Yog hais tias cov kab nruab nrab ntawm cov vertices yog tib yam, ces, feem, txhua lub kaum sab xis yog sib npaug rau 60 degrees.
Obt-angled daim duab peb sab
Lub kaum sab xis ntawm daim duab peb sab yog ib txwm siab dua 90-degree lub kaum ntse ntse, tab sis tsawg dua lub kaum sab xis. Yog li, lub kaum sab xis yog nruab nrab ntawm 90 thiab 180 degrees.
Cov lus nug tshwm sim: puas muaj ntau dua ib lub kaum obtuse hauv daim duab? Cov lus teb yog nyob ntawm qhov chaw: tsis yog, vim tias cov lej ntawm cov ces kaum yuav tsum tsawg dua 1800. Yog tias ob lub ces kaum yog, piv txwv li, 95 degrees txhua, ces tsis muaj qhov chaw rau qhov thib peb.
Obtuse polygons sib npaug:
- yog tias ob tog thiab lub kaum sab xis ntawm lawv sib npaug;
- yog ib sab thiab ob lub ces kaum,nyob ib sab ces sib npaug;
- yog peb sab ntawm obtuse daim duab peb sab sib npaug.
Txoj kev obtuse daim duab peb sab
Nyob rau hauv txhua daim duab peb sab nrog obtuse kaum sab xis, muaj cov kab hu ua zoo heev. Thawj qhov yog qhov siab. Nws yog ib qho perpendicular los ntawm ib qho ntawm cov vertices mus rau sab sib txuas. Txhua qhov siab sib tsoo ntawm ib qho chaw, uas yog hu ua orthocenter. Hauv daim duab peb sab nrog obtuse kaum sab xis, nws yuav nyob sab nraum daim duab nws tus kheej. Raws li rau cov ces kaum ntse, qhov nruab nrab muaj nyob rau hauv daim duab peb sab nws tus kheej.
Ib kab ntxiv yog qhov nruab nrab. Qhov no yog ib txoj kab kos los ntawm sab saum toj mus rau qhov nruab nrab ntawm qhov sib thooj. Tag nrho cov nruab nrab converge nyob rau hauv ib daim duab peb sab, thiab qhov chaw ntawm lawv ua ke yog qhov nruab nrab ntawm lub ntiajteb txawj nqus ntawm xws li ib tug polygon.
Bisector - ib kab sib faib ib nrab ntawm obtuse kaum sab xis thiab tus so. Qhov kev sib tshuam ntawm peb kab no ib txwm tshwm sim hauv daim duab nws tus kheej thiab txhais tau tias yog qhov chaw nruab nrab ntawm lub voj voog uas sau rau hauv daim duab peb sab.
Thiab, qhov nruab nrab ntawm lub voj voog uas tau piav qhia nyob ib ncig ntawm daim duab tuaj yeem tau txais los ntawm peb qhov nruab nrab ntawm qhov perpendiculars. Cov no yog cov kab uas tau poob los ntawm qhov nruab nrab ntawm cov kab sib txuas ntawm cov vertices. Qhov kev sib tshuam ntawm peb qhov nruab nrab perpendiculars nyob rau hauv daim duab peb sab nrog obtuse lub kaum sab xis yog sab nraum daim duab.
