b)
Apply double-angle formula: .
(Substitute )
\ \
(Rewrite the expression with common denominator)
The exact value of .
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![\"italic](\"http://www.wiris.com/demo-aspx/pluginwiris3/fckeditor_wiris/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.aspx?formula=0b86ca5ccb244d44aa2f7e2d6216235b.png\")
.![\"equal](\"http://www.wiris.com/demo-aspx/pluginwiris3/fckeditor_wiris/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.aspx?formula=f03f5a282a2aaaa6be48de615ca8c3f1.png\")
(Substitute ![\"italic](\"http://www.wiris.com/demo-aspx/pluginwiris3/fckeditor_wiris/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.aspx?formula=a218e0ca763a2fd9c42bbe8818973bab.png\")
)![\"equal](\"http://www.wiris.com/demo-aspx/pluginwiris3/fckeditor_wiris/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.aspx?formula=b23f7c14e98a8419d0c822224ca5aa12.png\")
\ \
![\"equal](\"http://www.wiris.com/demo-aspx/pluginwiris3/fckeditor_wiris/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.aspx?formula=2f761cb7edc44a302d34341351f75326.png\")
(Rewrite the expression with common denominator)![\"equal](\"http://www.wiris.com/demo-aspx/pluginwiris3/fckeditor_wiris/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.aspx?formula=6d61695bb2ef90c4d4502cd97a0c35e1.png\")
![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
.