Daim duab peb sab yog ib qho ntawm cov duab yooj yim hauv geometry. Nws yog ib txwm ua kom paub qhov txawv ntawm cov duab peb sab (ib lub kaum ntawm qhov sib npaug ntawm 90 0), cov kaum sab xis thiab obtuse (lub kaum sab xis tsawg lossis ntau dua 90 0feem), sib npaug thiab isosceles.
Thaum xam ntau yam, siv cov ntsiab lus geometric thiab ntau npaum li cas (sine, nruab nrab, vojvoog, perpendicular, thiab lwm yam)
Lub ncauj lus rau peb txoj kev kawm yuav yog qhov siab ntawm daim duab peb sab isosceles. Peb yuav tsis delve rau hauv cov ntsiab lus thiab cov ntsiab lus, peb tsuas yog luv luv piav qhia txog cov ntsiab lus tseem ceeb uas yuav tsum tau nkag siab lub ntsiab lus.
Yog li, daim duab peb sab isosceles suav tias yog daim duab peb sab uas qhov loj ntawm ob sab qhia los ntawm tib tus lej (sib npaug ntawm sab). Ib daim duab peb sab isosceles tuaj yeem mob, obtuse, lossis txoj cai. Nws tuaj yeem ua tau sib npaug (txhua sab ntawm daim duab yog sib npaug ntawm qhov loj). Koj tuaj yeem hnov ntau: txhua daim duab peb sab sib npaug yog isosceles, tab sis tsis yog tag nrhoisosceles - sib npaug.
Qhov siab ntawm ib daim duab peb sab yog qhov perpendicular poob ntawm lub ces kaum mus rau sab nraud ntawm daim duab. Qhov nruab nrab yog ib ntu kos los ntawm kaum ntawm daim duab mus rau qhov nruab nrab ntawm sab nraud.
Dab tsi zoo kawg li ntawm qhov siab ntawm daim duab peb sab isosceles?
- Yog tias qhov siab poob mus rau ib sab yog qhov nruab nrab thiab ib qho bisector, ces daim duab peb sab no yuav raug suav hais tias yog isosceles, thiab rov qab: daim duab peb sab yog isosceles yog tias qhov siab poob mus rau ib sab yog ob qho tib si bisector. thiab ib qho nruab nrab. Qhov siab no hu ua qhov siab loj.
- Qhov siab poob rau ntawm sab (sib npaug) sab ntawm daim duab peb sab isosceles zoo ib yam thiab tsim ob daim duab zoo sib xws.
- Yog tias koj paub qhov siab ntawm daim duab peb sab isosceles (raws li, qhov tseeb, ntawm lwm yam) thiab sab ntawm qhov siab no tau qis dua, koj tuaj yeem pom thaj tsam ntawm qhov polygon no. S=1/2 (chc)
Qhov siab ntawm daim duab peb sab isosceles siv li cas hauv kev suav? Cov khoom ntawm nws kos rau nws lub hauv paus ua rau cov lus hauv qab no muaj tseeb:
- Lub ntsiab qhov siab, ua tib lub sijhawm tus nruab nrab, faib lub hauv paus ua ob ntu sib npaug. Qhov no tso cai rau peb kom paub cov nqi ntawm lub hauv paus, thaj tsam ntawm daim duab peb sab tsim los ntawm qhov siab, thiab lwm yam.
- Ua ib qho perpendicular, qhov siab ntawm daim duab peb sab isosceles tuaj yeem suav hais tias yog ib sab (ceg) ntawm daim duab peb sab tshiab. Paub qhov loj ntawm txhua sab, raws li Pythagorean theorem (tag nrhopaub qhov piv ntawm cov squares ntawm ob txhais ceg thiab hypotenuse), koj tuaj yeem xam tus lej tus nqi ntawm qhov siab.
Dab tsi yog qhov siab ntawm daim duab peb sab? Feem ntau, daim duab peb sab isosceles, qhov siab ntawm qhov uas peb xav tau, tsis tas yuav yog li hauv nws cov ntsiab lus. Yog li ntawd, rau nws, tag nrho cov qauv siv rau cov nuj nqis, xws li, tsis poob lawv qhov tseeb. Koj tuaj yeem xam qhov ntev ntawm qhov siab, paub qhov luaj li cas ntawm cov ces kaum thiab sab, qhov loj ntawm ob sab, thaj tsam thiab sab, nrog rau cov lej ntawm lwm yam. Qhov siab ntawm daim duab peb sab yog sib npaug rau ib qho piv txwv ntawm cov nqi no. Nws tsis tsim nyog muab cov qauv rau lawv tus kheej, nws yooj yim mus nrhiav tau lawv. Tsis tas li ntawd, muaj qhov tsawg kawg nkaus ntawm cov ntaub ntawv, koj tuaj yeem nrhiav cov txiaj ntsig xav tau thiab tsuas yog tom qab ntawd pib nrog kev suav ntawm qhov siab.
