Te kimi i te horahanga o te porowhita: tauira me nga tauira

porohita he ahua āhuahanga; te huinga tohu i runga i te rererangi e takoto ana i roto i te porowhita.

tātai rohe

pūtoro

Te horahanga porowhita (S) he rite ki te hua o te tau π me te tapawhā o tōna pūtoro.

S = π ⋅ r ²

Putoro porohita (r) he wahanga raina e hono ana i tona pokapū me tetahi tohu o te porowhita.

Tuhipoka: mō ngā tātaitanga te uara o tētahi tau π whakaawhiwhia ki te 3,14.

Ma te diameter

Ko te horahanga o te porowhita ko te hauwha o te hua o te tau π me te tapawha o tona diameter:

Porohita diameter (d) e rite ana ki te rua irirangi (d = 2r). He wahanga raina tenei e hono ana i nga tohu e rua i runga i te porowhita.

He tauira mahi

Tūmahi 1

Kimihia te horahanga o te porowhita me te 9 cm te radius.

Te whakatau:

Ka whakamahia e matou te tauira e uru ana te radius:

S = 3,14 ⋅ (9 cm)² = 254,34cm².

Tūmahi 2

Kimihia te horahanga o te porowhita me te 8 cm te diameter.

Te whakatau:

Ka whakamahia e matou te tauira e puta ai te diameter:

S = 1/4 ⋅ 3,14 ⋅ (8 cm)² = 50,24cm².