Dalam Geometri, oktagon atau segi delapan (atau astakona) adalah sebuah segi banyak atau poligon yang mempunyai delapan sisi. Sebuah segi delapan beraturan mempunyai simbol Schläfli {8}.
L
=
2
cot
π
8
a
2
=
2
(
1
+
2
)
a
2
≃
4.828
a
2
.
{\displaystyle L=2\cot {\frac {\pi }{8}}a^{2}=2(1+{\sqrt {2}})a^{2}\simeq 4.828\,a^{2}.}
d
1
=
2
⋅
r
r
=
4
+
2
2
⋅
a
≈
2,613
⋅
a
{\displaystyle d_{1}=2\cdot r_{\mathrm {r} }={\sqrt {4+2{\sqrt {2}}}}\cdot a\approx 2{,}613\cdot a}
d
2
=
2
⋅
r
l
=
(
1
+
2
)
⋅
a
≈
2,414
⋅
a
{\displaystyle d_{2}=2\cdot r_{\mathrm {l} }=(1+{\sqrt {2}})\cdot a\approx 2{,}414\cdot a}
r
l
=
1
+
2
2
⋅
a
≈
1,207
⋅
a
{\displaystyle r_{\mathrm {l} }={\frac {1+{\sqrt {2}}}{2}}\cdot a\approx 1{,}207\cdot a}
r
r
=
1
2
⋅
4
+
2
2
⋅
a
≈
1,307
⋅
a
{\displaystyle r_{\mathrm {r} }={\frac {1}{2}}\cdot {\sqrt {4+2{\sqrt {2}}}}\cdot a\approx 1{,}307\cdot a}
α
=
360
∘
8
=
45
∘
{\displaystyle \alpha ={\frac {360^{\circ }}{8}}=45^{\circ }}
δ
=
180
∘
−
α
=
135
∘
{\displaystyle \delta =180^{\circ }-\alpha =135^{\circ }}
Segi delapan biasa dapat dibangun dengan batang gunung berapi . Kita membutuhkan dua belas batang ukuran 4, tiga batang ukuran 5 dan dua batang ukuran 6. Setiap sisi oktagon biasa memotong setengah sudut kanan di tengah lingkaran yang menghubungkan simpul-simpulnya. Dengan demikian luasnya dapat dihitung sebagai jumlah dari 8 segitiga sama kaki, yang mengarah ke hasil: Luas = 2 a 2 ( 2 + 1 ) {\displaystyle {\text{Luas}}=2a^{2}({\sqrt {2}}+1)}untuk segi delapan sisi a .
Asked by wiki @ 05/08/2021 in Matematika viewed by 20807 persons
Asked by wiki @ 02/08/2021 in Matematika viewed by 18598 persons
Asked by wiki @ 20/08/2021 in Matematika viewed by 14301 persons
Asked by wiki @ 12/08/2021 in Matematika viewed by 3606 persons
Asked by wiki @ 31/08/2021 in Matematika viewed by 2842 persons
Asked by wiki @ 12/08/2021 in Matematika viewed by 2592 persons
Asked by wiki @ 06/08/2021 in Matematika viewed by 2537 persons
Asked by wiki @ 03/08/2021 in Matematika viewed by 2474 persons
Asked by wiki @ 23/08/2021 in Matematika viewed by 2460 persons
Asked by wiki @ 03/08/2021 in Matematika viewed by 2458 persons
Asked by wiki @ 29/08/2021 in Matematika viewed by 2310 persons
Asked by wiki @ 10/08/2021 in Matematika viewed by 2307 persons
Asked by wiki @ 26/08/2021 in Matematika viewed by 2271 persons
Asked by wiki @ 09/08/2021 in Matematika viewed by 2246 persons
Asked by wiki @ 16/08/2021 in Matematika viewed by 2227 persons |