MATHEMATICS AND ORIGAMI

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