# Math Help - Solid of revolution around y-axis

1. ## Solid of revolution around y-axis

Let R be the area bounded by y = 1 /(4+x^2), y = 0, x = 0 and x =2. Calculate the volume of R if it is Revolved around the y-axis? Can someone help me with this? I know how to do it for the x-axis but this looks rather complicated... . Thanks!

2. ## Re: Solid of revolution around y-axis

method of cylindrical shells ...

$dV = 2\pi x \cdot \frac{1}{4+x^2} \cdot dx$

$V = 2\pi \int_0^2 \frac{x}{4+x^2} \, dx$