b No calculators Using the Disc or Washer method only find the exact value of the volume of the solid obtained by rotating the region enclosed by y x and x y about y 1 a Sketch the two curves on the same graph and shade in the region between them Show calculations for intersection points X Sketch the 3D volume that results when you rotate the shaded area from part a about y 1 Draw a typical disc or washer on this 3D sketch