Figure9b
Example3:
Derivea formulafor the volumeof the spherewith radius
Solution:
One way to find the formulais to use the disk method.Fromyour algebra,a circleof radius and center
at the originis givenby the formula
If we revolvethe circleaboutthe -axis,we will get a sphere.Usingthe disk method,we will obtaina formula
for the volume.Fromthe equationof the circleabove,we solvefor :
thus