parametriche asteroide
a = 2 (modificabile)
x =a*sin(t)^3
y = a*cos(t)^3

inserire a:= 2 





-------------------------

inserire
curva[a*sin(t)^3,a*cos(t)^3,t, 0, 6.28]

a = 4.4 (slider from -5 to 5, step 0.1)
b = CurveCartesian(a * sin(t)^(3), a * cos(t)^(3), t, 0, 6.28)