Math Help - Finding the Volumes

1. Finding the Volumes

1) Find the volume generated when the region is rotated around the x-axis:
-The region below the graph of y=sec(x) on [0,1/4(the pi symbol)].

-The region below the graph of y=(1-x^2)^1/2 on [-1,1].

I'm not sure where to start with these problems, so any help will be much appreciated. Thank you.

-M

2. Originally Posted by blurain
1) Find the volume generated when the region is rotated around the x-axis:
-The region below the graph of y=sec(x) on [0,1/4(the pi symbol)].

-The region below the graph of y=(1-x^2)^1/2 on [-1,1].

I'm not sure where to start with these problems, so any help will be much appreciated. Thank you.

-M
use the disk method.

The volume obtained by rotating a function $f(x)$ about the x-axis between the limits of $x = a$ and $x = b$, where $a \le b$, is given by:

$V = \pi \int_a^b [f(x)]^2~dx$