Mathematics and Origami
In ∆OAC
GIVEN OBTAINED
Ang. COA = 180 – BOA OC = 0,2949878º
AC = 1 Ang. OAC = 2,3909342º
2
1
OA=
In ∆EDA:
Ang. EDA = Ang. CDA = 113 , 69547
2
45.
180 45 =
−
− −
AngOAC
In ∆OCD:
GIVEN OBTAINED
OC = 0,2949878 OD = 0,3103317
Ang. COD = 90 – Ang. BOA = 81.869898º
Ang. ODC = 2 Ang. CDA – 180 = 47,39094º
Ang. OCD = 180 – Ang. COD – Ang. ODC = 50,739162º
Enneagon side = GH = ED =
2
1
- OD = 0,396775
=
+
=
2
2
tg
GH
OD
GH
α 0,3899744 ; α = 21.304515º
Value of regular enneagon central semiangle = 20º
The base GH becomes a bit greater than the other sides, which in turn are congruent to each
other. Same can be said about the angles.
D
A
O O
O
5 6
7
8
E
O
A
G
H
(^109)
11
✂
E
H
C
D
12
G
O
B
A