Barrons AP Calculus - David Bock

5. (a) To find the y-intercepts of the graph of P(t) = (9 − t^2 ,2t), let x = 9 − t^2 = 0, and solve: t = −3, 3.
   Then and P(3) = (0, 8).
   Draw a horizontal element of area as shown in the graph. Then:

(b)

(c) Use disks. Then ΔV = πx^2 Δy,