Ke ʻimi nei i ka ʻāpana o kahi pōʻai: formula a me nā laʻana

E kahalina he kii geometric; ka hoʻonohonoho o nā kiko ma ka mokulele e moe ana i loko o ka pōʻai.

ʻĀpana ʻāpana

ke kahahńnai o

ʻĀpana o ka pōʻai (S) ua like ia me ka huahelu π a me ka huinahalike o kona radius.

S = π ⋅ r ²

Poe radius (r) he māhele laina e hoʻopili ana i kona kikowaena a me kekahi kiko ma ka pōʻai.

'Ōlelo Aʻo: no ka helu ana i ka waiwai o kekahi helu π hoʻopuni ʻia a hiki i 3,14.

Ma ke anawaena

ʻO ka ʻāpana o ka pōʻai he hoʻokahi hapahā ka hua o ka helu π a me ka huinahalike o kona anawaena.

Poai anawaena (d) ua like me elua radii (d = 2r). He māhele laina kēia e hoʻopili ana i ʻelua mau kiko kūʻē ma ka pōʻai.

Nā laʻana o nā hana

Hana 1

E huli i ka ʻāpana o ka pōʻai me ka radius o 9 cm.

Hoʻoholo:

Hoʻohana mākou i ke ʻano i komo ai ka radius:

S = 3,14 ⋅ (9 knm)² = 254,34 knm².

Hana 2

E huli i ka ʻāpana o ka pōʻai me ke anawaena o 8 knm.

Hoʻoholo:

Hoʻohana mākou i ke ʻano i ʻike ʻia ai ke anawaena:

S = 1/4 ⋅ 3,14 ⋅ (8 knm)² = 50,24 knm².