The expression is .
(Apply sum of angles formula: )
(The values of )
(Multiply)
(Simplify)
is an identity.
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=83162b3004f37583a9832bf0af69917b.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0220dc555c4281346f6390cb4df40687.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=b182d8e830db7ab827e97debe76a2c47.png\")
)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=24fc8f81074842cbcae64a61534bcbaa.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=dc9cb76fa47853259049e08193a62996.png\")
(The values of ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=b4a4162fcd87f6a1faa937c6a6d1ac46.png\")
)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=9cc9136ba440707c9115aa4b908d7078.png\")
(Multiply)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=c748471f96a297d892b9abf2aad893b9.png\")
(Simplify)![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
is an identity.