Hauv kev tshaj tawm no, peb yuav xav txog yuav ua li cas xam qhov ib puag ncig ntawm lub trapezoid thiab txheeb xyuas cov piv txwv ntawm kev daws teeb meem.
Perimeter Formula
Lub perimeter (P) ntawm lub trapezoid yog sib npaug rau qhov sib npaug ntawm qhov ntev ntawm txhua sab.
P = a + b + c + d
- b и d - lub hauv paus ntawm lub trapezoid;
- a и с - nws ob sab.
Perimeter ntawm lub isosceles trapezoid
Hauv isosceles trapezoid, ob sab sib npaug (a uXNUMXd c), uas yog vim li cas nws tseem hu ua isosceles. Lub perimeter yog xam raws li nram no:
P = 2a + b + d or P = 2s + b + d
Perimeter ntawm ib lub duab plaub trapezoid
Txhawm rau xam qhov ib puag ncig, tib lub mis yog siv raws li scalene trapezoid.
P = a + b + c + d
Piv txwv ntawm cov dej num
Txoj Haujlwm 1
Nrhiav qhov ib puag ncig ntawm lub trapezoid yog tias nws cov hauv paus yog 7 cm thiab 10 cm thiab nws sab yog 4 cm thiab 5 cm.
Kev txiav txim siab:
Peb siv tus qauv qauv, hloov qhov paub sab ntev rau hauv nws: P u7d 10 cm + 4 cm + 5 cm + 26 cm uXNUMXd XNUMX cm.
Txoj Haujlwm 2
Lub perimeter ntawm lub isosceles trapezoid yog 22 cm. Nrhiav qhov ntev ntawm sab yog tias lub hauv paus ntawm daim duab yog 3 cm thiab 9 cm.
Kev txiav txim siab:
Raws li peb paub, lub perimeter ntawm ib tug isosceles trapezoid yog xam los ntawm cov mis: P = 2a + b + dQhov twg а - sab.
Nws qhov ntev muab faib ua ob yog: 2a = P - b - d = 22 cm - 3 cm - 9 cm = 10 cm.
Yog li ntawd, qhov ntev ntawm sab yog: a = 10 cm / 2 = 5 cm.
Aynan perimetri thiab formulasi yoq