Free response · Unit 8 Beta

A region between a parabola and an exponential curve

Area and volume · Part A: graphing calculator allowed · 9 points

The question

Name: ______________________   Date: ____________   A region between a parabola and an exponential curve (9 points)

Graph

The region RR between y=5−x2y = 5 - x^2 and y=ex/2y = e^{x/2}

Let f(x)=5−x2f(x) = 5 - x^2 and g(x)=ex/2g(x) = e^{x/2}. Let RR be the region enclosed by the graphs of ff and gg, as shown. The graphs intersect at x=ax = a and x=bx = b, where a<ba < b. A graphing calculator is required; use radian mode.
−2.5−2−1.5−1−0.50.511.522.5−112345xyfgR
  1. (a) Find the area of RR. [2 points]

  2. (b) Find the volume of the solid generated when RR is revolved about the horizontal line y=−2y = -2. [3 points]

  3. (c) Region RR is the base of a solid. For this solid, each cross section perpendicular to the xx-axis is a square. Find the volume of the solid. [2 points]

  4. (d) Write, but do not evaluate, an integral expression for the volume of the solid generated when RR is revolved about the horizontal line y=6y = 6. [2 points]