![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
The integral formula for the area of the surface of revolution is derived from the surface area formula for the lateral surface area of the frustum of right circular cone.
\The precalculus formula is the surface area formula for the lateral surface area of the frustum of
\right circular cone.
\Surface area ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=5ccc7a711020ea6b9a24c75068792a0a.png\")
, where ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=6dfb474bba4854b4b423f71a6deb8cc2.png\")
, which is average radius of the frustum and
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=07416f836bbbfedc19bb2d1568832327.png\")
is the length of the line segment of the frustum.
The representative element is ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=3eeb07b069f7d6a6afe1114d2ecd1fd0.png\")
.
![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
The representative element is ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=3eeb07b069f7d6a6afe1114d2ecd1fd0.png\")
.