Hauv tsab ntawv tshaj tawm no, peb yuav xav txog yuav ua li cas xam qhov ib puag ncig ntawm daim duab peb sab thiab txheeb xyuas cov piv txwv ntawm kev daws teeb meem.
Perimeter Formula
Perimeter (P) ntawm ib daim duab peb sab yog sib npaug rau cov lej ntawm qhov ntev ntawm tag nrho nws sab.
P = a + b + c
Perimeter ntawm daim duab peb sab isosceles
Ib daim duab peb sab isosceles yog daim duab peb sab uas nws ob sab sib npaug (cia peb coj lawv li b). Sab a, muaj qhov ntev sib txawv ntawm sab, yog lub hauv paus. Yog li, lub perimeter tuaj yeem xam raws li hauv qab no:
P = a + 2b
Perimeter ntawm ib daim duab peb sab equilateral
Ib daim duab peb sab sib npaug lossis txoj cai yog hu ua, uas txhua sab sib npaug (cia peb coj nws li a). Lub perimeter ntawm xws li ib daim duab yog xam raws li nram no:
P = 3a
Piv txwv ntawm cov dej num
Txoj Haujlwm 1
Nrhiav qhov ib puag ncig ntawm daim duab peb sab yog tias nws ob sab sib npaug: 3, 4 thiab 5 cm.
Kev txiav txim siab:
Peb hloov cov khoom uas paub los ntawm cov xwm txheej ntawm qhov teeb meem rau hauv cov qauv thiab tau txais:
P = 3 cm + 4 cm + 5 cm = 12 cm.
Txoj Haujlwm 2
Pom qhov ib puag ncig ntawm daim duab peb sab isosceles yog tias nws lub hauv paus yog 10 cm thiab nws sab yog 8 cm.
Kev txiav txim siab:
Raws li peb paub, sab ntawm daim duab peb sab isosceles sib npaug, yog li:
P = 10 cm + 2 ⋅ 8 cm = 26 cm.