3. The below diagram shows a solid with both rectan- gular and triangular cross sections. Suppose h = 16 cm, / = 18 cm, and w = 12 cm. W (a) Slice the solid parallel to the triangular faces and find the area of each slice and then setup the integral for finding the volume of the solid in terms of r, the distance of the slice from one end. (b) Repeat the previous analysis for horizontal slices. Instead of r, use y, the distance of a slice from the top