If you have a parametric equation grapher, graph the equations over the given intervals.
a. Epicycloid
$$
x=9 \cos t-\cos 9 t, \quad y=9 \sin t-\sin 9 t ; \quad 0 \leq t \leq 2 \pi
$$
b. Hypocycloid
$$
x=8 \cos t+2 \cos 4 t, \quad y=8 \sin t-2 \sin 4 t ; \quad 0 \leq t \leq 2 \pi
$$
c. Hypotrochoid
$$
x=\cos t+5 \cos 3 t, \quad y=6 \cos t-5 \sin 3 t ; \quad 0 \leq t \leq 2 \pi
$$