Contents
Ma'anoni na asali
Rectangle shi ne mai kusurwa huɗu wanda duk kusurwoyi daidai suke. Hakanan suna madaidaiciya kuma suna 90°.
Kewaye shine jimlar tsawon duk bangarorin polygon. Babban abin da aka yarda da shi shine babban harafin Latin P. A ƙarƙashin "P", yana da kyau a rubuta sunan adadi a cikin ƙananan haruffa don kada a ruɗe a cikin ayyukan da ke kan hanya.
Idan an ba da tsayin bangarorin a cikin raka'a daban-daban, ba za mu iya gano kewayen rectangle ba. Don haka, don ingantaccen bayani, ya zama dole a canza duk bayanan zuwa raka'a ɗaya na ma'auni.
Menene kewayen da aka auna a ciki?
- millimeter (mm);
- santimita (cm);
- dicimeter (dm);
- mita (m);
- kilomita (km) da sauran raka'o'in tsayi.
A cikin wannan ɗaba'ar, za mu yi la'akari da yadda za a lissafta kewayen rectangle da kuma nazarin misalan warware matsaloli.
Formula kewaye
Wurin (P) na rectangle daidai yake da jimillar tsawon duk sassansa.
P = a + b + a + b
Domin bangarorin wannan adadi daidai suke, ana iya wakilta dabarar kamar haka:
- Gefe biyu: P = 2*(a+b)
- Jimlar ƙima biyu na bangarorin: P = 2a+2b
Gajeren gajere shine tsayi / nisa na rectangle, mafi tsayin gefe shine tushe / tsayinsa.
Misalan ayyuka
Aiki 1
Nemo kewayen rectangle idan ɓangarorinsa sun kasance 5 cm da 8 cm.
Yanke shawara:
Muna maye gurbin sanannun ƙimar u2bu5binto da dabara kuma sami: P u8d 26 * (XNUMX cm + XNUMX cm) uXNUMXd XNUMX cm.
Aiki 2
Matsakaicin yanki na rectangle shine 20 cm, kuma ɗayan bangarorinsa shine 4 cm. Nemo gefen na biyu na adadi.
Yanke shawara:
Kamar yadda muka sani, P=2a+2b. Bari mu ce 4 cm gefe ne а. Don haka bangaran da ba a sani ba b, ninka ta biyu, ana ƙididdige su kamar haka: 2b u2d P - 20a u2d 4 cm - 12 * XNUMX cm uXNUMXd XNUMX cm.
Saboda haka, gefen b = 12 cm / 2 = 6 cm.
Matsalolin matsala
Kuma yanzu yi!
1. Daya gefen rectangle yana da 9cm kuma ɗayan yana da 11cm tsayi. Yadda za a gano kewaye?
Ta yaya za mu yanke shawara:
Idan a = 9, to b = 9 + 11;
Sannan b = 20 cm;
Bari mu yi amfani da dabara P = 2 × (a + b);
P = 2 × (9 + 20);
Amsa: 58 cm.
2. Nemo kewayen rectangle tare da bangarorin 30 mm da 4 cm. Bayyana amsar ku cikin santimita.
Ta yaya za mu yanke shawara:
Maida 30mm zuwa cm:
30 mm = 3 cm.
Yi amfani da dabara don kewayen rectangle:
P \u003d 3 + 4 + 3 + 4 \u003d 14 cm.
Amsa: P = 14 cm.
3. Nemo kewayen triangle tare da tarnaƙi 2 a ciki da 300 mm. Bayyana amsar ku cikin santimita.
Ta yaya za mu yanke shawara:
Bari mu canza tsayin gefen zuwa santimita:
2 dm = 20 cm, 300 mm = 30 cm.
Nemo kewaye ta amfani da dabara P = 2 × (a + b):
P \u003d 2 × (20 + 30) \u003d 2 × 50 \u003d 100 (cm).
Amsa: P = 100 cm.
