The identity is .
(Apply difference 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=b6d094851bbb4948109fca00ba7ac5ad.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=256f4301f09e48838b43f637da4349bf.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0f53900357785a6cfbbc9c5d2eef3570.png\")
)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=e9faf5fe4341dae71ffbe3cd58ab15fc.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=e3e98085838ebefc173afde97efc547b.png\")
(The values of ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=edc1e2eaa1baf1095d1e6be2a7f28f81.png\")
)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=101d68e10c855021ad0e94d0ab46bcbf.png\")
(Multiply)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=6b253d7a5a224fd9938ab9111119c038.png\")
(Simplify)![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=b6d094851bbb4948109fca00ba7ac5ad.png\")
is an identity.