Nrhiav thaj tsam ntawm ib lub xwmfab yog yooj yim tsuav koj paub qhov ntev ntawm nws sab, puag ncig, lossis kab pheeb ces kaum. Nov yog yuav ua li cas.
Cov kauj ruam
Txoj Kev 1 ntawm 3: Siv Qhov Ntev Ntawm Ib Sab
Kauj Ruam 1. Sau nws
Cia peb hais tias koj tab tom ua haujlwm nrog lub xwmfab nrog sab ntev ntawm 3 centimeter (1.2 in). Sau nws cia.
Kauj Ruam 2. Nkag siab cov qauv rau thaj tsam ntawm ib lub xwmfab (Thaj chaw = sab^2)
Txij li txhua lub xwmfab muaj qhov ntev sib npaug, koj tuaj yeem sib npaug qhov deb ntawm nws tus kheej. Yog tias qhov ntev ntawm ib sab yog 3 cm (1.2 in), tom qab ntawd koj tsuas yog yuav tsum tau square 3 centimeter (1.2 in) txhawm rau nrhiav thaj tsam ntawm ib lub xwmfab. 3 cm (1.2 in) x 3 cm (1.2 in) = 9 cm2.
Kauj Ruam 3. Nco ntsoov qhia koj cov lus teb hauv cov chav nyob
Tom qab ntawd koj ua tiav.
Squaring ib sab ntawm ib lub xwmfab yog tib yam li sib npaug ntawm lub xwmfab qhov siab nws lub hauv paus
Txoj Kev 2 ntawm 3: Siv Kev Paub Diagonal
Kauj Ruam 1. Siv qhov ntsuas ntawm qhov ntev ntawm kab pheeb ces kaum ntawm lub xwmfab
Kauj Ruam 2. Nkag siab cov mis rau thaj tsam uas siv kab pheeb ces kaum paub
Luas = (diagonal^2)/2.
Kauj Ruam 3. Muab qhov ntev ntawm kab pheeb ces kaum qhov ntsuas los ntawm nws tus kheej
Square qhov ntev ntawm kab pheeb ces kaum. Cia peb hais tias koj tab tom ua haujlwm nrog lub xwmfab nrog kab pheeb ces kaum uas yog 5 centimeter (2.0 in) ntev. Tam sim no, ntsuas tus lej no. 5 cm (2.0 in) x 5 centimeter (2.0 in) = 25 cm2.
Kauj Ruam 4. Muab tus lej tam sim no faib ua 2
Txuas ntxiv kev suav, 25 cm2 tau muab faib ua 2. Qhov no muab 12.5 cm2. Koj ua tiav
Txoj Kev 3 ntawm 3: Siv Kev Paub Ib puag ncig
Kauj Ruam 1. Muab thaj tsam ib ncig los ntawm 1/4 kom pom qhov ntev ntawm ib sab
Qhov no zoo ib yam li kev faib ib puag ncig los ntawm 4. Txij li thaum muaj plaub sab rau ib lub xwmfab thiab txhua sab yog qhov ntev sib npaug, koj tuaj yeem pom qhov ntev ntawm ib lub xwmfab tsuas yog muab faib ib puag ncig los ntawm 4. Cia peb hais ib puag ncig ntawm lub xwmfab koj tab tom ua haujlwm nrog yog 20 cm (7.9 in). Tsuas yog muab 20 cm (7.9 in) los ntawm 1/4: 20 centimeter (7.9 in) x 1/4 = 5 centimeter (2.0 in). Koj paub tias qhov ntev ntawm ib sab ntawm lub xwmfab yog 5 centimeter (2.0 in).
Kauj Ruam 2. Muab qhov ntev ntawm sab los ntawm nws tus kheej
Square qhov ntev ntawm sab. Tam sim no koj paub tias qhov ntev ntawm ib sab yog 5 centimeter (2.0 in), koj tuaj yeem square nws kom tau txais thaj tsam ntawm lub xwmfab. Luas = (5 cm)2 = 25 cm (9.8 nyob rau hauv).2