Answer
a. see graph; increases on $(0,2\pi)$; decreases on $(2\pi,4\pi)$
b. maximum at $(2\pi,4)$; minima at $(0,0)$ and $(4\pi,0)$
Work Step by Step
a. Using various $t$ values, we can graph the parametric equations as shown in the figure. We can identify that the function increases over $(0,2\pi)$ and decreases over $(2\pi,4\pi)$.
b. We can find a maximum at $(2\pi,4)$ and minima at $(0,0)$ and $(4\pi,0)$.