solid of revolution
disc integration is a method for calculating the volume of a solid of revolution of a solid-state material when integrating along an axis "parallel" to the axis of revolution
if the functions rotate around the
axis, the formula is
if the functions rotate around the
axis, the formula is

if the functions rotate around the
we start with a simple example, consider the function
if we were to rotate this function around the
axis we would get a Right Circular Cone:
to find the volume of this cone we use the disc integration formula, in this case
assume the function stopped at
and started at
so we find the volume in the interval

if we were to rotate this function around the
to find the volume of this cone we use the disc integration formula, in this case
assume the function stopped at
a circle is defined as
, consider the circle
if we were to rotate the circle
around the
axis we would get a ball
the upright quarter of a circle is defined as
consider the quarter of that circle whose formula is
if we were to rotate this around the
axis we would get half a ball and since this is easier to find the volume of we just find the volume using this quarter and multiply by 2 because it generates half a ball
in this case
, we find the volume using the formula:
so the volume of the ball is
if we were to rotate the circle
the upright quarter of a circle is defined as
consider the quarter of that circle whose formula is
if we were to rotate this around the
in this case
so the volume of the ball is
find the volume of produced by rotating the function
around the
axis in the interval
