In Problems a to c, a parametric representation of a curve is given. Eliminate the parameter to obtain the corresponding Cartesian equation. Sketch the given curve.
a. x = 61 + 2, y = 21; ∞ < t < ∞
b. r = 4t2, y = 4t; - 1 ≤ t ≤ 2
c. x = 4 sin t - 2, y = 3 cos t + 1; 0 ≤ t ≤ 2 π