Pictures used in the January 9 Lecture.

1. Mona Lisa (Leonardo da Vinci; from the cover of the book The Golden Section by Hans Walser)

2. A flower (Mammilaria huitzilo)

Question: How is this flower related to the Golden Mean ?

Answer:Through Fibonacci numbers.

3. Heaven and Hell (M.C.Escher, 1960)

4. Perspective drawing for the Adoration of the Magi (Da Vinci, around 1500)

(just for the fun of it)

1. Bisecting a line segment and drawing a perpendicular through the middle point You can control the animation by clicking over it (control-click on Mac; I don't "speak" other types).

2. Constructing a line parallel to a given line and through a given point. The first and the second circle are of equal radii, as are the third and the fourth circle.