Geometry Problem 655: Archimedes' Book of Lemmas: Proposition 15  Circle, Regular Pentagon, Radius
Let AB be the diameter of a circle, BC
a side of an inscribed regular pentagon, D the midpoint of the
arc BC. AB and CD meet in E; AD and BC meet in F. If FG is
perpendicular to AB, then EG is equal to the radius of circle.
Books of Lemmas Index
Proposition 1
Proposition 2
Proposition 3
Proposition 4
Proposition 5
Proposition 6
Proposition 7
Proposition 8
Proposition 9
Proposition 10
Proposition 11
Proposition 12
Proposition 13
Proposition 14
Proposition 15
