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	Math Help Forum > Pre-University Math Help > Trigonometry cos (x - y) User Name Save? Password Register Forum Rules FAQ Donate Members List Arcade Download MHF Flyer Search Today's Posts Mark Forums Read   Thread Tools Display Modes   #1   January 4th, 2009, 03:02 PM magentarita MHF Contributor   Join Date: Jul 2008 Location: NYC Posts: 1,489 Country: Thanks: 1,132 Thanked 23 Times in 16 Posts cos (x - y) When sin x = -8/17 and lies in quadrant 3 and cos y = -4/5 and lies in quadrant 2, find cos (x - y). Advertisement     #2   January 4th, 2009, 03:29 PM Mush Super Member   Join Date: Dec 2008 Location: Scotland Posts: 863 Country: Thanks: 6 Thanked 341 Times in 319 Posts Quote: Originally Posted by magentarita When sin x = -8/17 and lies in quadrant 3 and cos y = -4/5 and lies in quadrant 2, find cos (x - y). The Following 2 Users Say Thank You to Mush For This Useful Post: magentarita   #3   January 6th, 2009, 12:01 AM magentarita MHF Contributor   Join Date: Jul 2008 Location: NYC Posts: 1,489 Country: Thanks: 1,132 Thanked 23 Times in 16 Posts Tell me......... Quote: Originally Posted by Mush Tell me, what is the name of that formula?   #4   January 6th, 2009, 12:16 AM mathaddict Super Member   Join Date: Sep 2008 Location: West Malaysia Posts: 838 Country: Thanks: 232 Thanked 352 Times in 337 Posts Re: That is one of the additional formulas . The following users thank mathaddict for this useful post: magentarita   #5   January 6th, 2009, 08:18 AM magentarita MHF Contributor   Join Date: Jul 2008 Location: NYC Posts: 1,489 Country: Thanks: 1,132 Thanked 23 Times in 16 Posts ok... Quote: Originally Posted by mathaddict That is one of the additional formulas . I understand. Thanks. « Trigonometry Help (Identities) | Top | Need help with the following trig identity. » Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Trackbacks are Off Pingbacks are Off Refbacks are Off Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Pre-University Math Help     Pre-Algebra and Algebra     Geometry     Trigonometry     Pre-Calculus     Basic Statistics and Probability     Other topics University Math Help     Calculus     Analysis, Topology and Differential Geometry     Linear and Abstract Algebra     Number theory     Discrete Mathematics, Set Theory and Logic     Advanced Probability and Statistics     Advanced Applied Math     Differential Equations     Business Math     Other Advanced Topics Math Resources     LaTex Help     Mathematics Software Discussion     Calculator Discussion     Useful Math Websites     Mathematics News MHF Lounge     Chat Room         Live Chat     Problem of the Week     Pre-prints and other original work     Formal Debates         Proposals Challenges and Puzzles     Puzzles     Math Challenge Problems MHF Feedback and Announcements Forum     Question, Feedback and Comments     Announcements Our Other "Help Forums"     Physics Help Forum     Chemistry Help Forum All times are GMT -7. The time now is 08:23 PM. Contact Us - Math Help - Archive - Top Powered by vBulletin® Version 3.7.3 Copyright ©2000 - 2009, Jelsoft Enterprises Ltd. SEO by vBSEO 3.2.0 ©2008, Crawlability, Inc. ©2005 - 2009 Math Help Forum

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