In Exercises 19–20, four sets of parametric equations are given. Describe how their graphs are similar and different. Be sure to discuss orientation and ranges.
(a) x=cost y=sint, 0≤t≤2π
(b) x=cos(t2) y=sin(t2), 0≤t≤2π
(c) x=cos(1/t) y=sin(1/t), 0<t<1
(d) x=cos(cost) y=sin(cost), 0≤t≤2π