\
The expression is
.
\
Apply product-to-sum formula:
\
\
\
(Simplify)
\
The expression is
.
![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=63bcc80882e85ce4ab11fb8fc30c2fa2.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=374a454105949569e3eef038ac07368c.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=e5254b5409a73a06b0ba1ec0ebdeb175.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=bb560c4cfd1f4e618fe82cc09ef78f62.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=5995b243171cd8af3bb016382cc8a68f.png\")
(Simplify) ![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=4032fded1f769535ef3c736ff2211396.png\")
.