Yuav ua li cas mus nrhiav tau ntawm lub perimeter ntawm ib tug polygon?

Lwm ntawm cov thawj lub tsev kawm ntawv, muaj ntau yam nco ntsoov yuav ua li cas nrhiav tau ntawm lub perimeter ntawm tej geometric zoo: kawm kom txaus ntev ntawm nws sab thiab nrhiav tau lawv sum. Puag ncig hu ua lub sau ua ib pawg ntev ntawm lub dav hlau daim duab ciam teb rau lwm. Nyob rau hauv lwm yam lus, lub sum ntawm cov lengths ntawm nws sab. Lub tsev ntawm kev ntsuas yuav tsum sib haum mus rau ntawm lub perimeter ntawm lub tsev ntawm qhov kev ntsuas ntawm nws sab. polygon puag ncig mis muaj rau hauv daim P = ib + b + c ... + n, nyob qhov twg P - perimeter, tab sis ib tug, b, c thiab n - ntev ntawm ib sab. Txwv tsis pub xam ncig (los yog puag ncig lub voj voog) siv cov mis P = 2 * π * r, qhov twg r - voos kheej-kheej, thiab π - qhov tooj ntawm kwv yees li 3.14. Xav txog tej yam yooj yim piv txwv uas qhia tau tias yuav ua li cas nrhiav tau cov perimeter. Raws li ib qho piv txwv peb yuav nrhiav xws li ib tug square, duab plaub, daim duab peb sab, parallelogram thiab voj voog.

Yuav ua li cas mus nrhiav tau ntawm lub perimeter ntawm lub square

Square hu ua txoj cai quadrangle, uas yog muaj sib npaug rau tag nrho cov sab thiab cov ces kaum. Txij li thaum tag nrho cov sab ntawm cov square yog muaj sib npaug, lub sum ntawm cov lengths ntawm nws cov sab yuav xam los ntawm cov mis P = 4 * ib tug, thiab nyob qhov twg - qhov ntev ntawm ib sab. Yog li, ib tug square puag ncig nrog sab ntawm 16.5 cm yog P = 4 * 16.5 = 66 cm. Yog li ntawd nws yog ua tau rau xam ntawm lub perimeter ntawm equilateral rhomb.

Yuav ua li cas mus nrhiav tau ntawm lub perimeter ntawm ib tug duab plaub

Duab plaub - ib tug duab plaub uas lub ces kaum yog 90 degrees. Nws yog lub npe hu hais tias nyob rau hauv no daim duab, tus duab plaub, lub lengths ntawm lub sab yog muaj sib npaug nyob rau hauv officers. Yog hais tias lub dav thiab qhov siab ntawm cov duab plaub yog tib yam ntev, nws yog hu ua ib tug square. Feem ntau hu ua tus loj tshaj ntev rectangle sab, thiab lub dav - tsawg tshaj plaws. Yog li, kom tau txais lub perimeter ntawm lub duab plaub, nws yog tsim nyog los ob npaug rau tus nqi ntawm nws cov dav thiab qhov siab: P = 2 * (a + b), qhov chaw uas ib tug - qhov siab, thiab b - tus dav. Vim muaj cov duab plaub, ib sab ntawm uas yog ntev thiab yog 15 cm dav thiab lwm yam nrog rau lub teeb tus nqi yog 5 cm, peb tau puag ncig sib npaug zos rau P = 2 * (15 + 5) = 40 cm.

Yuav ua li cas mus nrhiav tau ntawm lub perimeter ntawm daim duab peb sab

Daim duab peb sab tsim ntawm peb kab theem uas txuas cov ntsiab lus (lub vertices ntawm daim duab peb sab), tsis dag nyob rau hauv tib txoj kab ncaj nraim. Ib tug daim duab peb sab yog hu ua equilateral hais tias tag nrho peb yog muaj sib npaug rau nws txhais tes, thiab ceskaum yog ob tug sib npaug zos sab. Yuav kom nrhiav tau ntawm lub perimeter ntawm ib tug equilateral daim duab peb sab, koj yuav tsum muab qhov ntev ntawm nws sab los ntawm 3: P = 3 * ib tug, qhov chaw uas ib tug - ib qho ntawm nws cov sab. Yog hais tias lub sab ntawm daim duab peb sab yog tsis sib npaug zos, nws yog tsim nyog los nqa tawm qhov sib ntxiv lag luam: P = ib + b + c. Ntawm lub perimeter ntawm ib tug ceskaum daim duab peb sab nrog sab 33, 33 thiab 44, ntsig txog, yuav muaj sib npaug zos rau: P = 33 + 33 + 44 = 110 cm.

Yuav ua li cas mus nrhiav tau ntawm lub perimeter ntawm ib tug parallelogram

Parallelogram - ib tug quadrilateral nrog opposite sab pairwise mus tib seem. Square, pob zeb diamond thiab duab plaub nrhiav yog tshwj xeeb no. Yam txawv sab ntawm txhua parallelogram yog muaj sib npaug, li ntawd, yuav xam nws cov puag ncig siv cov mis mos P = 2 (a + b). Nyob rau hauv ib tug parallelogram nrog sab ntawm 16 cm thiab 17 cm sum ntawm lub sab los yog puag ncig sib npaug zos rau P = 2 * (16 + 17) = 66 cm.

Yuav ua li cas mus nrhiav tau qhov ib ncig

Circumference yog ib tug raug kaw kab, tag nrho cov ntsiab lus uas yog nyob rau ntawm sib npaug zos deb ntawm qhov chaw. Qhov ntev ntawm ib lub voj voog thiab nws txoj kab uas hla yog yeej ib txwm muaj tib lub ratio. Qhov no piv yog qhia los ntawm ib tug tsis tu ncua, yog sau cia los ntawm txhais tau tias ntawm cov tsiaj ntawv thiab π yog kwv yees li 3,14159. Tshawb ntawm lub perimeter ntawm lub voj voog yuav ua tau cov khoom ntawm lub voos kheej-kheej los ntawm 2 thiab π. Nws hloov tawm hais tias ib lub vojvoog ntawm ib lub voj voog nrog ib tug ntev ntawm 15 cm yuav tsum sib npaug zos rau P = 2 * 3,14159 * 15 = 94,2477