Compute the volume of the solid obtained by rotating the region below the graph of f(x) = e-a/2 about the x-axis for -∞

Find the volume of the solid formed by revolving about the x-axis the region bounded by the graph of f(x) = √sin x and the x-axis (0 ≤ x ≤ π/2).

Both 2 & 3 please

Let f be the function defined by f(x)=6/1+x^2. Let R be the shaded region bounded by the graph of f and the horizontal line y=3, as shown in the figure above.  (a) Find the area of R. (b) Write, but do not evaluate, an integral expression for the volume of the solid generated when R is rotated about the horizontal line y=7 (c) Let h(x) be the vertical distance between the point (x,f(x)) and the horizontal line y=3. Find the rate of change of h(x) with respect to x at x=2