Find the exact value of .
The value of .
Rewrite the expression.
.
Apply cosine double angle identity : .
![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=fe875063b350635c7b02d7478cf24fca.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=52a98794f536a3352c5fa0069b8df0cd.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=9645733615e535df9306a0d13a1c329a.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=83b6914af4b108aab12ff514534ec58f.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=4047ea995a8b3f3c928fa296ed654894.png\")