Ib qho ntawm thawj cov qauv kawm hauv lej yog yuav ua li cas xam cov cheeb tsam ntawm ib daim duab plaub. Nws kuj yog qhov feem ntau siv. Rectangular nto yog nyob ib ncig ntawm peb, yog li peb feem ntau yuav tsum paub lawv cheeb tsam. Yam tsawg kawg kom paub seb cov xim muaj puas txaus los pleev xim rau hauv pem teb.
thaj chaw twg nyob qhov twg?
Yog hais tias peb tham txog qhov uas tau lees paub thoob ntiaj teb, ces nws yuav yog ib square meter. Nws yog qhov yooj yim los siv thaum xam cov cheeb tsam ntawm phab ntsa, qab nthab lossis hauv pem teb. Lawv qhia thaj chaw tsev.
Thaum nws los txog rau cov khoom me, ces square decimeters, centimeters los yog millimeters yog qhia. Qhov kawg xav tau yog tias daim duab tsis loj dua tus ntiv tes.
Thaum ntsuas thaj tsam ntawm ib lub nroog lossis lub tebchaws, square kilometers yog qhov tsim nyog tshaj plaws. Tab sis kuj tseem muaj cov chav uas siv los qhia qhov loj ntawm thaj chaw: ares thiab hectares. Thawj tug kuj hu ua ib puas.
Yuav ua li cas yog muab ob sab ntawm lub duab plaub?
Qhov no yog txoj hauv kev yooj yim tshaj plaws los suav cov cheeb tsam ntawm ib daim duab plaub. Nws yog txaus los muab ob qho tib si paub qhov tseem ceeb: ntev thiab dav. Cov qauv zoo li no: S=ab. Ntawm no, cov tsiaj ntawv a thiab b qhia qhov ntev thiab qhov dav.
Ib yam li ntawd, thaj tsam ntawm ib lub xwmfab, uas yog qhov tshwj xeeb ntawm cov duab plaub, suav nrog. Txij li tag nrho nws sab yog sib npaug, cov khoom yuav dhau los ua square ntawm tsab ntawv a.
Yuav ua li cas yog tias daim duab kos rau ntawm daim ntawv checkered?
Nyob rau hauv qhov xwm txheej no, koj yuav tsum vam khom cov cell hauv cov duab. Los ntawm lawv tus lej, nws tuaj yeem yooj yim los xam thaj tsam ntawm daim duab plaub. Tab sis qhov no tuaj yeem ua tiav thaum ob sab ntawm cov duab plaub sib npaug nrog cov kab ntawm tes.
Feem ntau muaj xws li ib txoj hauj lwm ntawm lub duab plaub, nyob rau hauv uas nws ob sab yog inclined nyob rau hauv relation mus rau kab ntawm daim ntawv. Tom qab ntawd tus naj npawb ntawm cov hlwb yog qhov nyuaj rau kev txiav txim siab, yog li kev suav ntawm thaj tsam ntawm daim duab plaub yuav nyuaj.
Koj thawj zaug yuav tsum paub txog thaj tsam ntawm daim duab plaub, uas tuaj yeem kos los ntawm cov hlwb raws nraim ntawm qhov muab. Nws yog qhov yooj yim: muab qhov siab thiab qhov dav. Tom qab ntawd rho tawm los ntawm qhov tshwm sim tus nqi thaj tsam ntawm tag nrho cov duab peb sab sab xis. Thiab muaj plaub ntawm lawv. Los ntawm txoj kev, lawv raug xam raws li ib nrab ntawm cov khoom ntawm ob txhais ceg.
Qhov kawg tshwm sim yuav muab thaj tsam ntawm cov duab plaub.
Yuav ua li cas yog tias ob sab tsis paub, tab sis nws kab pheeb ces kaum tau muabthiab lub kaum sab xis ntawm kab pheeb ces kaum?
Ua ntej nrhiav thaj tsam ntawm ib daim duab plaub, hauv qhov xwm txheej no, koj yuav tsum suav nws sab thiaj li siv cov qauv uas twb paub lawm. Ua ntej koj yuav tsum nco ntsoov cov cuab yeej ntawm nws cov kab pheeb ces kaum. Lawv sib npaug thiab bisect lub ntsiab lus ntawm kev sib tshuam. Koj tuaj yeem pom hauv daim duab uas cov kab pheeb ces kaum faib cov duab plaub rau hauv plaub daim duab peb sab isosceles, uas yog sib npaug ntawm cov khub rau ib leeg.
Qhov sib npaug ntawm cov duab peb sab yog txhais ua ib nrab ntawm kab pheeb ces kaum, uas paub. Ntawd yog, hauv txhua daim duab peb sab muaj ob sab thiab lub kaum sab xis ntawm lawv, uas tau muab rau hauv qhov teeb meem. Koj tuaj yeem siv lub theorem cosine.
Ib sab ntawm daim duab plaub yuav suav nrog cov qauv uas siv qhov sib npaug ntawm daim duab peb sab thiab cov cosine ntawm lub kaum sab xis muab. Txhawm rau xam tus nqi thib ob, tus cosine yuav tsum tau muab los ntawm lub kaum sab xis sib npaug ntawm qhov sib txawv ntawm 180 thiab lub kaum sab xis paub.
Tam sim no qhov teeb meem ntawm yuav ua li cas xam thaj tsam ntawm ib daim duab plaub los ntawm qhov yooj yim sib npaug ntawm ob sab tau.
Yuav ua li cas yog lub cheeb tsam raug muab rau hauv qhov teeb meem?
Feem ntau, tus mob kuj qhia qhov piv ntawm qhov ntev thiab qhov dav. Cov lus nug ntawm yuav ua li cas xam thaj tsam ntawm ib lub duab plaub, qhov no, yog yooj yim dua nrog ib qho piv txwv.
Xav tias hauv qhov teeb meem ib puag ncig ntawm ib daim duab plaub yog 40 cm. Nws tseem paub tias nws qhov ntev yog ib thiab ib nrab npaug ntau dua nws qhov dav. Koj yuav tsum paub nws cheeb tsam.
Txoj kev daws teeb meem pib nrog kev sau cov qauv perimeter. Nws yog qhov yooj yim dua los sau nws raws li qhov sib npaug ntawm qhov ntev thiab qhov dav, txhua qhov sib npaug los ntawmob sib cais. Qhov no yuav yog thawj qhov sib npaug hauv qhov system yuav daws tau.
Qhov thib ob yog cuam tshuam nrog qhov piv txwv paub los ntawm tus mob. Thawj sab, uas yog, qhov ntev, yog sib npaug rau cov khoom ntawm qhov thib ob (dav) thiab tus naj npawb 1, 5. Qhov kev sib npaug no yuav tsum tau hloov pauv mus rau hauv cov qauv rau ib puag ncig.
Nws hloov tawm tias nws yog sib npaug rau cov lej ntawm ob lub monomial. Qhov thib ib yog cov khoom ntawm 2 thiab qhov dav tsis paub, qhov thib ob yog cov khoom ntawm cov lej 2 thiab 1, 5 thiab tib qhov dav. Hauv qhov sib npaug no, tsuas muaj ib qho tsis paub - qhov no yog qhov dav. Koj yuav tsum suav nws, thiab tom qab ntawd siv qhov sib npaug thib ob los xam qhov ntev. Txhua yam uas tseem tshuav yog muab ob tug lej no kom paub seb thaj tsam ntawm daim duab plaub.
Kev suav muab cov txiaj ntsig hauv qab no: dav - 8 cm, ntev - 12 cm, thiab cheeb tsam - 96 cm2. Tus lej kawg yog cov lus teb ntawm qhov kev txiav txim siab.
