This question concerns the family of curves with parametric equations:[br][br][math]x=a\times cos\left(t\right)+3cos\left(\frac{2t}{3}\right)[/math][br][math]y=a\times sin\left(t\right)-3sin\left(\frac{2t}{3}\right)[/math][br][math]0\le t<6\pi[/math][br][br]Sketch the curves in the cases a=2, a=3 and a=4 on separate axes.[br][br]State one common feature of these three curves. State one distinctive feature of the curve for the case a=2.