18. Find the volume of the solid generated by rotating the region R about the y -axis. R is the region bounded by y = sin2 x + 1, y = 0, the y -axis, and x = 3vit. See the graph below. a. Sketch the region R and the solid generated by rotating R. b. Decide what method you'll be using. Will it be the washer (cross section/ slice) or shell (can) method. Will it be done with dx or dy? c. Depending on the method you chose, sketch a sample washer or shell. d. Set up the integral and find the volume