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
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

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

find the volume of produced by rotating the function around the axis in the interval