Yuav Ua Li Cas Thiaj Li Pom Qhov Sab Nraud ntawm Daim Duab Geometric

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Yuav Ua Li Cas Thiaj Li Pom Qhov Sab Nraud ntawm Daim Duab Geometric
Yuav Ua Li Cas Thiaj Li Pom Qhov Sab Nraud ntawm Daim Duab Geometric

Video: Yuav Ua Li Cas Thiaj Li Pom Qhov Sab Nraud ntawm Daim Duab Geometric

Video: Yuav Ua Li Cas Thiaj Li Pom Qhov Sab Nraud ntawm Daim Duab Geometric
Video: qhia txog kev faib hau qhua su 2024, Lub peb hlis ntuj
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Perimeter yog ntsuas ntawm qhov nrug ib ncig ntawm ob-seem duab. Txhawm rau xam qhov puag ncig ntawm lub duab plaub, piv txwv li, ntxiv qhov loj ntawm nws plaub sab (ob kab rov tav thiab ob kab ntsug). Txhawm rau txiav txim siab tus nqi ib puag ncig ntawm lwm yam duab tsis yog ncig, ua tib yam, ntxiv qhov ntau thiab tsawg ntawm txhua sab sab nraud. Paub paub ntsuas ntsuas ib puag ncig ntawm thaj chaw twg yog qhov muaj txiaj ntsig zoo hauv lub neej txhua hnub. Xav txog tias ib tus neeg xav tsim lub laj kab laj kab. Txhawm rau yuav qhov ntsuas qhov tseeb ntawm cov ntaub ntawv, nws yuav tsum tau suav tag nrho ib puag ncig ntawm thaj chaw. Yog li, txhawm rau txuag kev taug kev mus rau lub tsev tsim khoom ntim khoom, lossis los kawm rau qhov kev xeem, kawm paub xam thaj tsam tam sim no!

cov kauj ruam

Ntu 1 ntawm 2: Nrhiav Ib puag ncig ntawm Feem Ntau Cov Duab Duab

Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 1
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 1

Kauj Ruam 1. Nrhiav qhov loj ntawm txhua sab

Txawm hais tias muaj cov qauv los pab txhawb kev suav ntawm ib puag ncig ntawm qee cov duab geometric, hauv paus, nws txaus los ntxiv ob sab. Qhov tseem ceeb pib nrog yog paub qhov loj ntawm txhua sab.

  • Piv txwv li, pentagon, piv txwv li, koj yuav tsum paub qhov loj me ntawm txhua ntawm nws tsib sab.
  • Txawm hais tias rau qhov tsis txaus ntseeg nees nkaum-ob tog nws tuaj yeem suav tau ib puag ncig, tsuav koj paub qhov loj ntawm txhua sab.
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 2
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 2

Kauj Ruam 2. Ntxiv qhov loj ntawm txhua sab ua ke

Qhov no siv tau rau ib yam khoom uas tsis yog ncig. Ua raws li kev qoj ib ce:

  • Dab tsi yog qhov puag ncig ntawm lub pentagon uas nws sab muaj cov hauv qab no: A = 4, B = 2, C = 3, D = 3, thiab E = 2?
  • Teb: 4 + 2 + 3 + 3 + 2 = 14, yog li P (puag ncig) = 14.
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 3
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 3

Kauj Ruam 3. Ua haujlwm nrog qhov sib txawv

Nrhiav qhov puag ncig txawm tias thaum ob sab tau sawv cev los ntawm qhov sib txawv. Xav txog daim duab peb sab uas ob sab muaj qhov tseem ceeb: 14a, 11b thiab 7a:

  • Suav txhua sab: P = 14a + 11b + 7a;
  • Ua ke cov ntsiab lus sib xws: P = (14a + 7a) + 11b;
  • P = 21a + 11b.
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 4
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 4

Kauj Ruam 4. Nco ntsoov cov ntsuas ntsuas

Hauv kev tawm dag zog, nws tsis yog ib txwm paub tias ntsuas ntsuas twg yog siv los laij ib puag ncig (millimeters, centimeters, meters, thiab lwm yam). Txawm li cas los xij, hauv lub ntiaj teb tiag, qhov no tseem ceeb heev uas yuav tsum xav txog (koj yuav yuav 10 laj kab li cas?). Hauv qhov kev ua pentagon, piv txwv li, yog tias chav tsev siv los sawv cev rau qhov tseem ceeb ntawm ob sab yog centimeters, qhov tshwm sim yuav tsum tau sau ua: P = 14 cm.

Ntu 2 ntawm 2: Kawm cov qauv rau xam ib puag ncig

Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 5
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 5

Kauj Ruam 1. Nrhiav qhov puag ncig ntawm lub voj voog

Qee cov lej tsis tu ncua muaj cov qauv tsuas yog ua kom yooj yim dua, thaum lwm tus, zoo li lub voj voog, xav kom siv cov mis. Ib puag ncig ntawm lub voj voog hu ua ib puag ncig, thiab txhawm rau nrhiav nws, siv cov mis: C (ib puag ncig) = 2πr.

  • Thawj kauj ruam yog nrhiav lub vojvoog ntawm lub voj voos, uas yog qhov ntev ntawm qhov chaw mus rau ntug, txiav txim siab los ntawm txoj kab ncaj ncaj ntu.
  • π yog tus lej tsis tu ncua, sib npaug rau 3, 14. Txawm tias yog tus lej zauv uas tsis kawg, ib tus tuaj yeem siv cov lus nthuav qhia (3, 14) kom tau txais qhov kwv yees kwv yees.
  • Rau lub vojvoog ntawm lub vojvoog 4 cm, suav yuav yog: C = 2 x 3, 14 x 4 = 25, 12 cm.
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 6
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 6

Kauj Ruam 2. Nrhiav qhov puag ncig ntawm daim duab peb sab

Rau qhov no, txais yuav qhov sib npaug: P = a + b + c. Piv txwv, yog tias daim duab peb sab muaj cov ntsuas hauv qab no: a = 20 cm, b = 11 cm thiab c = 9 cm, peb tuaj txog ntawm P = 20 + 11 + 9 = 40 cm.

Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 7
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 7

Kauj Ruam 3. Xam ib puag ncig ntawm ib lub xwmfab

Txhua sab ntawm ib lub xwmfab sib npaug, yog li cov qauv yog P = 4x, qhov twg x piv rau qhov loj ntawm txhua sab.

Hauv ib lub xwmfab ntawm sab x = 3 cm, cov hlaws yuav saib: P = 4 x 3 = 12 cm

Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 8
Nrhiav qhov puag ncig ntawm Cov Duab Kauj Ruam 8

Kauj Ruam 4. Nrhiav qhov puag ncig ntawm daim duab plaub

Hauv ib lub duab plaub, ob sab sib luag yog qhov loj ib yam, yog li cov qauv yog: P = 2a + 2b, qhov twg “a” sib npaug kab rov tav thiab “b” sib npaug ntsug. Rau ib lub duab plaub nrog ob sab a = 8 cm thiab b = 5 cm:

  • P = (2 x 8) + (2 x 5);
  • P = 16 + 10;
  • P = 26 hli
  • Qhov sib npaug P = 2 (a + b) yuav tsim cov lus teb tib yam: 2 (8 + 5) = 2 (13) = 26 cm.
Nrhiav Ib puag ncig ntawm Cov Duab Kauj Ruam 9
Nrhiav Ib puag ncig ntawm Cov Duab Kauj Ruam 9

Kauj Ruam 5. Nrhiav thaj tsam ib puag ncig ntawm quadrilaterals

Plaub fab yog ib daim duab duab uas muaj plaub sab kaw. Cov no suav nrog cov duab plaub, plaub fab, trapezoids, parallelograms, deltoids thiab pob zeb diamond. Saib peb qhov sib npaug muaj:

  • Rau plaub fab plaub fab nrog txhua sab sib txawv, xws li qhov tsis sib xws trapezius: P = a + b + c + d;
  • Rau ib qho nrog txhua sab sib npaug: P = 4x (zoo ib yam li cov xwm txheej);
  • Rau cov uas muaj ob sab sib npaug sib npaug (zoo li lub duab plaub): P = 2a + 2b lossis P = 2 (a + b).

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