![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
The rate of change in radius is ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=964ab77bc9720b3a9087f1e42d4f75fc.png\")
constant.
Area of the circle is ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=9ef972970a1675675e92f1d17d8a1a60.png\")
.
Differentiate on each side with respect to ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=a16a536fef06fc1158565c7288e36387.png\")
.
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0419e1d236233e54f752248af707dd5e.png\")
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=f6257aac4b1243e8ffabeab77fa66338.png\")
.
Substitute ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=990bdcaf4992f291078c1dc72e9a0911.png\")
in the derivative function.
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=d822bf89e73b5fc553791b51e506d981.png\")
Since ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=8d88be8e02929b5d1785df971276bad5.png\")
is constant .The value of ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=a1be16c5e8198241007f09fab6abdb76.png\")
depend on the value of the radius.
![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
The value of depend on the value of the radius.