11.4 Construction of regular pentagon 327
11.4 Construction of regular pentagon
LetOAandOYbe two perpendicular radii of a circle, centerO.
1.Mark the midpointMofOYand bisect angleOMAto intersect
OAatP.
2.Construct the perpendicular toOAatPto intersect the circle atB
andE.
A
Y
M
P
B
E
O
C
D
ThenA,B,Eare three adjacent vertices of a regular pentagon in-
scribed in the circle. The remaining two vertices can be easily con-
structed.