Indlela yokuthola selilonke

Umugqa elivaliwe uhlukanisa indiza yaba izingxenye ezimbili ukuphela (ngaphakathi - umbuthano) kuphelele futhi akupheli (line ngaphandle), inqobo nje uma it has izakhiwo eziningana ethize, ngokuthi umbuthano. Ngokwesibonelo, kudingeka ukuhambisana equidistance amaphuzu elele kulo mugqa, kusuka kwelinye iphuzu maphakathi circle. Ukuze uthole indiza kuchazwe emjikelezweni, kukhona ezinye izici ambalwa. Lezi zihlanganisa:

• engaba (ibanga ukusuka kunoma yiliphi iphuzu elele ke, enkabeni, r);
• ubukhulu (umugqa sokuhlukanisa umbuthano zibe izingxenye ezimbili alinganayo, edabula amaphuzu amabili futhi umbuthano maphakathi mbuthano, d);
• endaweni anda ezibonisa ubukhulu mbuthano, S;
• ubude umugqa avaliwe echaza umbuthano (ebekwe incwadi Ḻ).

Ngakho, Ḻ akuyona nje isici ambalwa of circle, kodwa umugqa avaliwe, ngakho impendulo yombuzo - indlela ukufunda selilonke, kusebenza kokubili imiqondo yejeyomethri.

I Ran ibanga ngento indiza sangaphandle ivaliwe ijika round ukuma ilingana ubude umugqa ozungeza kuwo. Lokhu kuhlola ambalwa of selilonke isetshenziswa nesilinganiso eziphathekako, kodwa nalapho ucabangela abstract ngamajamo weJiyomethri. Igama elithi linencazelo ekhethekile ngokuba nolwazi be-Jomethri Trigonometric. It libhekisela ubuningi ngokomzimba, okuyinto ibe yintfo lekhetsekile into efana ipherimitha. NgesiGreki, elithi umsindo «περίμετρον» ( «mbuthano») noma «περιμετρέο» ( «isilinganiso emhlabeni"). Ipherimitha (indiza sibalo nganoma yisiphi umumo) futhi selilonke (ukuma isiyingi ngoba ukuma Planar) lilingana Ubude bobunjwa umngcele. icala Special (umngcele emjikelezweni) has isici efanayo ibanga noma endleleni. Ukuze ukufunda isihloko esithi "Indlela Yokuzigcina ukubala ubude Umbuthano", kubalulekile ukukhumbula amayunithi futhi inguqulo yabo.

Ngokwe-international simiso SI, iyiphi indlela noma ibanga kulinganiswa ngamamitha. Lokhu lisisakhiwo, kodwa kukhona okunye. Ngakho-ke afanele labo abakhetha izinkinga theory ne practical ku "indlela yokuthola ubude obungazungeza" ukuhola nobuhlobo babo:

• 1 ikhilomitha = 1000 amamitha = 10000 = 100000 decimeters amasentimitha = 1000000 amamilimitha angu;
• 1 imayela = 1,609344 amakhilomitha = 1609.344 16093.44 amamitha decimeters = = = 160,934.4 sentimitha amamilimitha angu 1.609.344;
• 1 ft = 30,48 amasentimitha = 304,8 amamilimitha angu decimeters = 3,048 = 0,3048 = 0,0003048 amamitha amakhilomitha.

Zikhona nezinye amayunithi eziningi zokulinganisa: eBritish (noma American), ubudala isiRashiya, isi-Greek, isi-Japanese nabanye. Ukuze ngabo ukwenza izibalo, kutuswa ukusebenzisa ulwazi ngemuva.

Ukuze yonke imibuthano libhekene ngento eyodwa, eyasungulwa ososayensi endala. Inani labantu okufanele lifinyelelwe obuphelele ukuze ubukhulu wombuthano uhlale inombolo njalo. Kwaphela isikhathi eside ososayensi sisebenzisa izindlela ezahlukahlukene (futhi okwamanje isofthiwe ezikhethekile kanye nobuchwepheshe bama-computer), uzama ukusungula ukubaluleka esiqondile ngaleyo nombolo. Ivame okhonjiswe incwadi ngesiGreki «π» (liphinyiselwe njengoba pi). Inani eseduze ngezikhathi ezahlukahlukene nhlobonhlobo, kodwa kwakuhlale kancane ezingaphezu kwezintathu. I π inombolo dimensionless. Namuhla, ososayensi bakwazi ukusungula emva iphuzu zamadesimali emamaki isigidintathu eziyishumi. Lokhu ukunemba kuyadingeka ngoba izibalo eziyinkimbinkimbi zezibalo. Kodwa ekuxazululeni izinkinga weJiyomethri, lapho kulindeleke ukuba baphendule umbuzo - indlela ukuthola selilonke, ziba mandla ekusebenziseni le nombolo ezingu ezinhlanu noma ezimbili: π ≈ 3,14159 ≈ 3,14.

Kuyaziwa ukuthi Ḻ / D = π = 3,14 noma Ḻ / 2 R = π = 3,14 ezaziwayo. Ngakho-ke kulula ukuphendula umbuzo - indlela yokuthola ubude obungazungeza engaba 1 imitha noma 2 decimeter, noma ububanzi 5 ngamasentimitha. Sikhetha iphindwe kabili engaba noma ububanzi we π inombolo. Ukuze zonke izimo ezintathu ifomula Ḻ = π • D = 3,14 • D noma Ḻ = 2 • π • R = 2 • 3,14 • R Imiphumela etholwe izibalo ezilandelayo:

1. Ḻ = 3.14 • 2 • 1 = 6.28 m;
2. Ḻ = 3.14 • 2 • 2 DM = 12,56;
3. Ḻ = 3,14 • 5 = 15.7 cm.

Umsebenzi eliqukethe umbuzo - indlela yokuthola ubude selilonke, uma yaziwa, engaba yayo noma ububanzi, kodwa endaweni eyaziwayo embuthanweni, okuncane eziyinkimbinkimbi, kodwa kungase futhi ingaxazululwa. Kwaphela isikhathi eside kwaziwa ukuthi endaweni isiyingi elilingana umkhiqizo π futhi esigcawini engaba noma ububanzi yesine isikwele: S = π • ṟ² noma S = π • d ² / 4.

Kubalwa engaba lokuqala R = √ (S / π) noma ububanzi D = √ (4 • S / π), khona-ke kubalwa obuphelele circumferential. Ungabona isibonelo amacala amabili lapho endaweni embuthanweni ilingana 12,56 m² futhi 78,5 cm²:

1. R = √ (12,56 / 3,14) = 2 m, kuyilapho Ḻ = 3.14 • 2 • 2 = 12.56 m noma D = √ (4 • 12,56 / 3,14) = 4 m, ke Ḻ = 3,14 • 4 = 12.56 m.
2. R = √ (78,5 / 3,14) = 5 cm ke Ḻ = 3.14 • 5 • 2 = 31.4 cm noma D = √ (4 • 78.5 / 3.14) = 10 cm ke Ḻ = 3,14 • 10 = 31.4 cm.