Txhais thiab cov khoom ntawm qhov nruab nrab ntawm daim duab peb sab txoj cai

Hauv tsab xov xwm no, peb yuav txiav txim siab lub ntsiab lus thiab cov khoom ntawm qhov nruab nrab ntawm ib daim duab peb sab txoj cai kos rau lub hypotenuse. Peb kuj tseem yuav tshuaj xyuas ib qho piv txwv ntawm kev daws teeb meem los sib sau ua ke cov khoom siv theoretical.

Kev txiav txim siab qhov nruab nrab ntawm daim duab peb sab txoj cai

theem nrab yog kab ntu uas txuas lub vertex ntawm daim duab peb sab mus rau qhov nruab nrab ntawm sab nraud.

Txoj cai daim duab peb sab yog daim duab peb sab uas ib lub kaum sab xis yog (90 °) thiab lwm qhov yog mob (<90 °).

Cov khoom ntawm qhov nruab nrab ntawm daim duab peb sab txoj cai

Khoom Muaj Khoom 1

Median (AD) nyob rau hauv ib daim duab peb sab yog kos los ntawm lub vertex ntawm txoj cai kaum (∠LAC) mus rau lub hypotenuse (BC) yog ib nrab ntawm hypotenuse.

• BC = 2 AD
• AD = AB = DC

Qhov yuav tshwm sim: Yog hais tias qhov nruab nrab yog sib npaug rau ib nrab ntawm sab uas nws yog kos, ces sab no yog lub hypotenuse, thiab daim duab peb sab yog txoj cai-angled.

Khoom Muaj Khoom 2

Qhov nruab nrab kos rau lub hypotenuse ntawm txoj cai daim duab peb sab yog sib npaug rau ib nrab ntawm lub hauv paus square ntawm cov sum ntawm cov squares ntawm ob txhais ceg.

Rau peb daim duab peb sab (saib daim duab saum toj no):

Nws ua raws los ntawm thiab Cov khoom 1.

Khoom Muaj Khoom 3

Qhov nruab nrab poob rau ntawm lub hypotenuse ntawm txoj cai daim duab peb sab yog sib npaug rau lub vojvoog ntawm lub voj voog ncig ncig daim duab peb sab.

Cov. BO yog ob qho tib si nruab nrab thiab lub vojvoog.

Nco ntsoov: Kuj tseem siv tau rau daim duab peb sab txoj cai, tsis hais hom daim duab peb sab.

Piv txwv ntawm qhov teeb meem

Qhov ntev ntawm qhov nruab nrab kos nyob rau hauv lub hypotenuse ntawm txoj cai daim duab peb sab yog 10 cm. Thiab ib qho ntawm ob txhais ceg yog 12 cm. Nrhiav qhov perimeter ntawm daim duab peb sab.

tshuaj

Lub hypotenuse ntawm daim duab peb sab, raws li nram no los ntawm Cov khoom 1, ob zaug qhov nruab nrab. Cov. nws sib npaug: 10 cm ⋅ 2 = 20 cm.

Siv lub Pythagorean theorem, peb pom qhov ntev ntawm ob txhais ceg (peb coj nws li "B", lub npe nrov ceg - rau “rau”, hypotenuse - rau “Nrog”):

b² =c² - thiab² = 20² - 12² = 256.

Thiaj li, lub b Luas = 16 cm.

Tam sim no peb paub qhov ntev ntawm txhua sab thiab peb tuaj yeem xam qhov ib puag ncig ntawm daim duab:

P_△ Luas = 12 cm + 16 cm + 20 cm = 48 cm.