Ungayifumana njani i-perimeter ye-polygon?

Kusuka esikolweni esiprayimari, abaninzi bakhumbula indlela yokufumana umgama we- geometric figure: okwaneleyo ukwazi ubude bawo onke macala kunye nokufumana isamba sabo. I-perimeter ubude bomda wemida yesithuthi. Ngamanye amazwi, esi sibalo sobude bamacala abo. Iyunithi yokulinganisa i-perimeter imele ifane neyunithi yokulinganisa kwamacala ayo. Ifom ye-perimeter ye-polygon inefomu P = a + b + c ... + n, apho iP perimeter, kwaye apha, b, c n nubude belicala ngalinye. Ngaphandle koko, ubude bendulungu (okanye umjikelezo wesangqa) lubalwa: ifom p = 2 * π * r isetyenzisiwe, apho i-radius kunye ne-π inombolo ehlala rhoqo malunga ne-3.14. Makhe sibone imizekelo elula ebonisa indlela yokufumana umjikelezo. Njengesiqulatho, sithatha amanani anjengekwere, ixande, unxantathu, iparallelogram, kunye nesangqa.

Indlela yokufumana umjikelezo wekwere

Isikwere sisigxina esinexesha eliqhelekileyo, apho onke amacala kunye nama-angles alingana. Ekubeni zonke iinxalenye zesikwere zilingana, isixa sobude bamacala aso singabalwa ngefomula P = 4 * a, apho ubude bomnye wamacala. Ngaloo ndlela, i- perimeter yesikwere ngapha nangama-16.5 cm yi-P = 4 * 16.5 = 66 cm. Ungakwazi kwakhona ukubala i-perimeter ye-rhombus equilateral.

Indlela yokufumana umjikelezo wexande

Ixande liyi-quadrilateral nazo zonke iinjenge ezilingana nama-90 degrees. Kuyaziwa ukuba kweso sibalo njengengxande, ubude bamacala balingana ngamabini. Ukuba ububanzi kunye nobude bexande babude ubude, ngoko kuthiwa yibala. Ngokuqhelekileyo ubude bexande lubizwa ngokuba luninzi kumacala, kwaye ububanzi bubuncinci. Ngaloo ndlela, ukuba ufumane umjikelezo wecangechunge, kufuneka uphindwe kabini ububanzi bayo ububanzi nobude: P = 2 * (a + b), apho ukuphakama kunye nobubanzi bubanzi. Ukuba nexande, elinye icala elingu-15 cm ubude kunye nolunye ububanzi kunye nexabiso elibekwe li-5 cm, sifumana i-perimeter elinganayo no-P = 2 * (15 + 5) = 40 cm.

Indlela yokufumana umjikelezo wesantathu

Inxantathu yenziwe ngamacandelo amathathu adibanisa kumanqaku (imiqobo yontathunxantathu) engayithethi kumgca ofanayo ngqo. Unxantathu kuthiwa ulinganayo, ukuba onke amacandelo ayo amathathu alinganayo, kwaye i-isosceles ukuba kukho amacala amabini alinganayo. Ukufumana i-perimeter yexantathu elinganayo, kuyimfuneko ukuphindaphinda ubude becala ngo-3: P = 3 *, apho enye yecala layo. Ukuba amacala enxantathu ayalingani kunye, kubalulekile ukwenza umsebenzi wokudibanisa: P = a + b + c. I-perimeter yexantathu ye-isosceles kunye namacandelo 33, 33 no-44, ngokulandelanayo, iya kuba: P = 33 + 33 + 44 = 110 cm.

Indlela yokufumana umjikelezo weparallelogram

I-parallelogram i-quadrilateral kunye namacandelwana ahlukeneyo. Isikwere, i-rhombus kunye nekontrane ziimeko ezithile zemifanekiso. Amacandelwana athileko nayiphi na ipallelogram ayalingana, ngoko ukubala i-perimeter yayo isebenzisa ifomu P = 2 (a + b). Kwi-parallelogram kunye namacala angama-16 cm kunye no-17 cm, isixa samacala, okanye i-perimeter, ngu-P = 2 * (16 + 17) = 66 cm.

Indlela yokufumana umjikelezo wesangqa

Isangqa ngumgca ovalwe, onke amanqaku afumaneka kumgama olinganayo ukusuka kwiziko. Umjikelezo kunye nobubanzi bawo buhlala bunomlinganiselo ofanayo. Lo mgangatho uboniswa rhoqo, obhaliweyo usebenzisa ileta π kwaye malunga ne-3.14159. I-perimeter yesangqa ingafumaneka kwimveliso yerhasi nge-2 kunye ne-π. Kuvela ukuba ubude besangqa ne-radius ye-15 cm kuya kufana no-P = 2 * 3.14159 * 15 = 94.2477