Hypocycloid prove that an epicycloid with "k" cusps moves snugly inside one with "k"+1 cusps. The evolute of a hypocycloid is an enlarged version of the hypocycloid itself, while the involute of a hypocycloid is a reduced copy of itself. The pedal of a hypocycloid with pole at the center of the hypocycloid is a rose curve. The isoptic of a hypocycloid is a hypocycloid. Curves similar to hypocyloids can be drawn with the Spirograph toy. Specifically, the Spirograph can draw hypotrochoids and epitrochoids. The Pittsburgh Steelers' logo, which is based on the Steelmark, includes three astroids (hypocycloids of four cusps).
Denys Ovenden the Collins Guide to Freshwater Life a small share in the Collins Fungi Guide. Denys was commissioned by the Open University to prepare a poster accompanying David Attenborough's BBC series Life in Cold Blood. After a period of 15 years’ work, Galápagos, a Guide to the Animals and Plants. This finally went to print after the addition of illustrations two other recently discovered rodents and the elusive pink iguana. Denys Ovenden Denys Ovenden was born on April 1, 1922. His preoccupation with drawing began very early, since there are drawings on the fly-leaves of books from that period. His natural