Draw the related diagram:
Observe the figure:
The area of the shaded region is .
Therefore, the correct choice is option .
The correct choice is option .
![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/userfiles/52-745-83(1).gif\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=11f90c5169d2552dd22ce08c0629189e.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=98222dc751b49d0673461fc7bdb1ee29.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0d25261cbf81e1c8bf5afdeff1f7b3e9.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=283b220bdb46f284105555bd373b8e09.png\")
.![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=283b220bdb46f284105555bd373b8e09.png\")
.