This question has been taxing me for some time. I am a first year Mathematics student in London and for some reason am struggling with the substitution needed to answer this question.

Q.

Find the volume of the solid of revolution obtained when the region undr the graph of f(x)= (1/x)sec(1/x), from x=3/pi to x=4/pi, is rotated about the x-axis. Give your answers to 2 decimal places.

Can anyone give me a breakdown of the answer please?

Chris