Daim duab geometric - lub duab plaub - tsis tau tsuas yog kev lej loj, tab sis kuj muaj kev faib tawm lub cev. Tom qab tag nrho, txhua yam uas tau muab rau hauv tsev kawm ntawv cov ntaub ntawv kawm muaj cov ntawv thov cuam tshuam. Yog li, piv txwv li, paub tias thaj tsam ntawm lub duab plaub yog dab tsi sib npaug, koj tuaj yeem yooj yim nrhiav txoj hauv kev ntawm lub cev thaum lub sij hawm ua kom nrawm nrawm. Yuav ua li cas? Tam sim no xav txog.
Qhov cheeb tsam ntawm ib hom ntawm daim duab yog xam nyob rau hauv ntau txoj kev. Hauv peb qhov xwm txheej, peb yuav tsum paub cov lej ntawm ob lub hauv paus thiab qhov siab. Qhov kawg yog ib sab, dag ntawm lub kaum sab xis. Hauv tag nrho, cov txiaj ntsig xav tau suav nrog hauv qab no:
S=(a+b)h/2
Tau kawg, qhov kev vam khom no tsis yog coj los ntawm lub qab nthab. Nws muaj peev xwm hais tias ib tug neeg paub txog lub midline, uas muaj ob qho tib si ib txwm thiab ib lub voj voog trapezoid. Yog hais tias nws yog denoted los ntawm tsab ntawv m, ces tus nqi yuav nrhiav tau raws li nram no: m=(a + b) / 2. Mentally txav ntu no mus. Ib yam dab tsi zoo li qhov ntev ntawm lub duab plaub uas paub yuav tig tawm. Nws yog nyob rau ntawm qhov txo rau qhov yooj yim tshaj plaws daim duab uas thawj muab dependence yog tsim. Feem ntau, cov qauv rau thaj tsam ntawm ib lub duab plaub yogtrapezoid qhia txog qhov muaj peev xwm hloov h (qhov siab) nrog qhov ntev ntawm sab ntawm lub kaum sab xis ntawm 90 degrees. Qee tus yuav tsum nkag siab tam sim ntawd tias qhov no yog qhov ncaj ncees los ntawm qhov sib npaug ntawm cov khoom no.
Thaum pib, peb twb tau hais txog qhov muaj peev xwm ntawm kev siv cov lej hauv physics. Tshwj xeeb, cov tub ntxhais kawm yuav tsum paub zoo txog lub hauv paus ntsiab lus ntawm kev ua kom nrawm nrawm. Ib daim duab trapezoid yog cov ntaub ntawv thaum pib tshaj tawm yog xoom, qhov acceleration yog tas li. Yog tias txoj haujlwm ntawm tes yuav tsum suav txoj kev taug kev hauv qhov xwm txheej zoo li no, koj tuaj yeem siv cov mis los nrhiav thaj chaw. Cia qhov sib txawv "a" qhia tag nrho cov kev taug kev. Nws yuav tsum tau hais tam sim ntawd tias peb tab tom ua haujlwm hauv Cartesian kev tswj hwm. Tom qab ntawd "b" yuav qhia txog lub sijhawm uas muaj qhov ceev tshaj plaws. Raws li, yog hais tias txog thaum kawg ntawm lub zog nws tseem nyob uniformly ceev, ces b=0. Rau h peb coj tus nqi ntawm qhov nrawm nrawm. Tom qab hloov qhov tseem ceeb, koj yuav tau txais txoj hauv kev, vim nws tuaj yeem suav nrog cov qauv S=V nruab nrabt. Tam sim no koj paub yuav ua li cas lub duab plaub yuav pab tau koj.
Yuav daws teeb meem, koj yuav tsum paub tsuas yog ob peb lub qauv rau daim duab hauv nqe lus nug. Piv txwv li, qhov sib npaug ntawm cov ces kaum ntawm ib sab inclined yog 180 degrees. Cov kab pheeb ces kaum nrog kev hwm rau ib sab yog lub hypotenuse ntawm txoj cai daim duab peb sab nrog ob txhais ceg. Nco ntsoov tias nyob deb ntawm ib qho quadrilateral, tshwj xeeb tshaj yog nyob rau hauvib lub voj voos trapezoid, koj tuaj yeem sau ib lub voj voog. Ntau lub ntsiab lus tau muab nyob rau hauv lub tsev kawm ntawv chav kawm, tab sis nws yog ib qho tsim nyog yuav tau rho tawm qhov tseem ceeb ntawm lawv. Piv txwv li, qhov tseeb hais tias lub duab plaub trapezoid muaj tag nrho cov khoom ntawm ib tug tsis tu ncua, tab sis kuj muaj ib co ntxiv nta. Piv txwv tias lub hauv paus yog plaub, sab yog peb, thiab kab pheeb ces kaum txuas lawv yog 5. Los ntawm Pythagorean theorem, 33 + 44=55. Los ntawm qhov no nws ua raws li peb muaj lub voj voos trapezoid.
Yog li, koj tau ntsib nrog lwm daim duab geometric. Nws tsis yog qhov tsim nyog los cim cov qauv rau kev nrhiav nws thaj chaw, nws txaus kom nkag siab txog lub hauv paus ntsiab lus ntawm kev suav.
