"Epi-HypoCycloids"

"Initial radii"

a:=12

b:=1

"Circle centered at origin of radius a.  Plot t in [0,2pi].  Set plot scale 6~
.4 horz & 4 vert."

[a*COS(t),a*SIN(t)]

"Epicycloid with a radius of original circle and b radius of rotating circle.~
"

[(a+b)*COS(t)-b*COS((a+b)/b*t),(a+b)*SIN(t)-b*SIN((a+b)/b*t)]

"Hypocycloid with a radius of original circle and b radius of rotating circle~
."

[(a-b)*COS(t)+b*COS((a-b)/b*t),(a-b)*SIN(t)-b*SIN((a-b)/b*t)]

"Try various values for a and b.  Also vary c and d where t is in [c,d]."