Nrhiav thaj tsam ntawm ib lub xwmfab yog qhov yooj yim heev yog tias koj paub qhov ntev ntawm nws ob sab, puag ncig, lossis kab pheeb ces kaum. Nov yog yuav nrhiav nws li cas.
Kauj ruam
Txoj Kev 1 ntawm 3: Siv Sab Ntev
Kauj Ruam 1. Sau cov lus ntev
Piv txwv tias ib lub xwmfab muaj sab ntev txog 3 cm. Sau nws cia.
Kauj Ruam 2. Paub cov mis rau nrhiav thaj tsam ntawm ib lub xwmfab (thaj tsam = sab^2)
Txij li txhua lub xwmfab muaj tib sab ntev, koj tsuas yog xav kom sib npaug qhov ntev ntawm lub xwmfab los ntawm nws tus kheej. Yog hais tias sab ntawm ib lub xwmfab yog 3 cm, tom qab ntawd koj tsuas yog xav tau square 3 cm txhawm rau nrhiav thaj tsam ntawm lub xwmfab. 3 cm x 3 cm = 9 cm2.
Kauj Ruam 3. Tsis txhob hnov qab sau cov chav nyob hauv daim ntawv plaub fab
Koj ua tiav lawm.
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Squaring ob sab ntawm ib lub xwmfab yog tib yam li sib npaug qhov siab ntawm lub xwmfab los ntawm lub hauv paus.
Nrhiav thaj tsam ntawm Square Square 3Bullet1
Txoj Kev 2 ntawm 3: Siv Kev Paub Kab Kab Ntev
Kauj Ruam 1. Ntsuas qhov ntev ntawm kab pheeb ces kaum ntawm lub xwmfab
Kauj Ruam 2. Muab cov txiaj ntsig ntawm kev ntsuas kab pheeb ces kaum ntev ntawm lub xwmfab los ntawm nws tus kheej
Square qhov ntev ntawm kab pheeb ces kaum. Piv txwv tias ib lub xwmfab muaj kab pheeb ces kaum ntawm 5 cm. Tam sim no, square qhov ntev ntawm kab pheeb ces kaum. 5 cm x 5 cm = 25 cm2.
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 sab
Qhov no zoo ib yam li kev faib ib puag ncig los ntawm 4. Vim tias lub xwmfab muaj plaub sab thiab txhua sab yog qhov ntev tib yam, koj tuaj yeem pom sab sab ntawm ib lub xwmfab yooj yim los ntawm kev faib ib puag ncig los ntawm 4. Cia peb hais tias thaj tsam ntawm ib lub xwmfab yog 20 cm yog. Sib npaug 20 cm los ntawm 1/4: 20 cm x 1/4 = 5 cm. Yog li, koj pom tias qhov ntev ntawm ib sab ntawm lub xwmfab yog 5 cm.
Kauj Ruam 2. Muab qhov ntev ntawm ib sab ntawm lub xwmfab los ntawm nws tus kheej
Square sab ntev. Txij li koj twb paub lawm tias sab ntev yog 5 cm, koj tuaj yeem square nws kom pom thaj tsam ntawm lub xwmfab. Luas = (5 cm)2 Luas = 25 cm2
