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

Hauv tsab xov xwm no, peb yuav txiav txim siab lub ntsiab lus ntawm qhov nruab nrab ntawm daim duab peb sab, sau nws cov khoom, thiab tseem txheeb xyuas cov piv txwv ntawm kev daws teeb meem los sib sau cov ntaub ntawv theoretical.

Cov ntsiab lus

Txhais qhov nruab nrab ntawm daim duab peb sab

theem nrab yog ib txoj kab uas txuas lub vertex ntawm ib daim duab peb sab nrog lub midpoint ntawm sab opposite ntawd vertex.

  • BF yog qhov nruab nrab kos rau sab AC.
  • AB = FC

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

Base nruab nrab - lub ntsiab lus ntawm kev sib tshuam ntawm qhov nruab nrab nrog rau sab ntawm daim duab peb sab, hauv lwm lo lus, qhov nruab nrab ntawm sab no (point F).

cov khoom nruab nrab

Khoom 1 (lub ntsiab)

Vim Yog tias daim duab peb sab muaj peb sab thiab peb sab, ces muaj peb qhov nruab nrab, feem. Lawv txhua tus sib tshuam ntawm ib qho chawO), uas yog hu ua nruab nrab or center ntawm gravity ntawm daim duab peb sab.

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

Nyob rau ntawm qhov kev sib tshuam ntawm cov neeg nruab nrab, txhua tus ntawm lawv tau muab faib ua qhov sib piv ntawm 2: 1, suav los ntawm sab saum toj. Cov.:

  • AO = 2 AO
  • OB = 2
  • CO = 2 OD

Khoom Muaj Khoom 2

Qhov nruab nrab faib daim duab peb sab rau 2 daim duab peb sab ntawm qhov sib npaug.

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

S1 =S2

Khoom Muaj Khoom 3

Peb tus neeg nruab nrab faib daim duab peb sab ua 6 daim duab peb sab ntawm qhov sib npaug.

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

S1 =S2 =S3 =S4 =S5 =S6

Khoom Muaj Khoom 4

Qhov tsawg tshaj plaws nruab nrab sib haum mus rau sab loj tshaj plaws ntawm daim duab peb sab, thiab vice versa.

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

  • AC yog qhov ntev tshaj plaws, yog li qhov nruab nrab BF - qhov luv tshaj.
  • AB yog qhov luv tshaj sab, yog li qhov nruab nrab CD - ntev tshaj plaws.

Khoom Muaj Khoom 5

Piv txwv li peb paub txhua sab ntawm daim duab peb sab (cia peb coj lawv li a, b и c).

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

nruab nrab ntev makos rau sab a, tuaj yeem pom los ntawm cov qauv:

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

Piv txwv ntawm cov dej num

Txoj Haujlwm 1

Qhov chaw ntawm ib qho ntawm cov duab tsim los ntawm kev sib tshuam ntawm peb qhov nruab nrab hauv ib daim duab peb sab yog 5 cm.2. Nrhiav thaj tsam ntawm daim duab peb sab.

tshuaj

Raws li cov cuab yeej 3, sib tham saum toj no, vim yog kev sib tshuam ntawm peb qhov nruab nrab, 6 daim duab peb sab yog tsim, sib npaug hauv cheeb tsam. Yog li ntawd:

S△ Luas = 5 cm2 ⋅ 6 = 30 cm2.

Txoj Haujlwm 2

Sab ntawm daim duab peb sab yog 6, 8 thiab 10 cm. Nrhiav qhov nruab nrab kos rau sab nrog qhov ntev ntawm 6 cm.

tshuaj

Cia peb siv cov qauv uas tau muab rau hauv cov khoom 5:

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

Sau ntawv cia Ncua