lej yog kev kawm nyuaj heev. Yog vim li ntawd qee tus tub ntxhais kawm yuav muaj teeb meem nkag siab txog qee lub ntsiab lus. Kab lus no yog sau los pab cov niam txiv piav txog tej yam nyuaj rau tus menyuam. Yog li, tsab xov xwm yuav tham txog yuav ua li cas nrhiav thaj chaw thiab thaj tsam ntawm ib lub duab plaub.
Yuav ua li cas thiaj nrhiav tau ib puag ncig ntawm daim duab plaub?
Lub cheeb tsam yog dab tsi? Cov no yog qhov ntev ntawm txhua sab ntxiv ua ke. Yuav ua li cas nrhiav tau lub perimeter? Txhawm rau pom nws, koj yuav tsum ntxiv qhov ntev ntawm txhua sab. Tab sis nws yog ntev thiab tsis yooj yim. Yog vim li ntawd lawv thiaj tsim ib lub mis tshiab. Qhov tseeb yog hais tias ob sab dag opposite ib leeg yog sib npaug. Yog li koj tuaj yeem siv ob qhov ntev thiab ob qhov dav ntawm lub duab plaub thiab ntxiv rau lawv. Thiab yog li ntawd ib qho qauv tshiab tau yug los. Lub perimeter nyob rau hauv nws yog denoted los ntawm tsab ntawv P. Yog li, P=2(a + b), qhov twg a yog qhov ntev ntawm lub duab plaub, b yog nws qhov dav. Txhawm rau kuaj koj tus kheej, daws cov teeb meem hauv qab no: ntev 6 centimeters, dav - 4. Nrhiav ib puag ncig ntawm cov duab plaub. Yog koj nkag siab lub ntsiab lus thiab daws qhov teeb meem kom raug, ces koj yuav tau 20 cm.
Tseem yuav tshwm simXws li qhov xwm txheej: muab ib sab thiab ib puag ncig, koj yuav tsum pom ob sab ntawm lub duab plaub. Txoj haujlwm no tuaj yeem daws tau ob txoj hauv kev. Ua ntej: P=2a + 2b, li no b=(P-2a): 2. Qhov thib ob xaiv: P=2(a + b), li no b=P: 2-a. Yog tag nrho. Txhua yam khoom ntawm lub ncauj lus tau muab. Tsis muaj dab tsi nyuab, puas yog?
Tshaj tawm ntawm ib daim duab plaub
cheeb tsam yog dab tsi? Hauv cov ntsiab lus yooj yim, cheeb tsam yog tus lej ntawm ib qho kev ntsuas hauv ib lub duab plaub (lossis lwm yam duab). Qhia thaj chaw los ntawm tsab ntawv S. Ces S=ab, qhov twg a yog qhov ntev, b yog qhov dav ntawm daim duab plaub.
Thiab yog thaj chaw thiab ib sab twg paub? Tam sim no cia peb paub. Ib cheeb tsam yog dab tsi? Yog lawm, ua haujlwm. Dab tsi yog a thiab b? Tau kawg, multipliers. Yuav ua li cas thiaj nrhiav tau qhov tsis paub zoo? Nws yog ib qho tsim nyog los faib cov haujlwm ua kom paub. Yog li a=S:b, ib yam li b=S:a. Txhawm rau xyaum, daws qhov teeb meem. Qhov ntev ntawm lub vaj yog 6 meters, thiab thaj tsam yog 30 m 2. Nrhiav qhov dav ntawm daim phiaj vaj.
Yog li, kab lus no tau tham txog yuav ua li cas nrhiav thaj chaw thiab thaj tsam ntawm lub duab plaub uas nws qhov dav thiab ntev paub.
