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	Math Help Forum > Pre-University Math Help > Trigonometry Trig Identity 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 21st, 2009, 04:29 PM DaCoo911 Newbie   Join Date: Jan 2009 Posts: 14 Country: Thanks: 6 Thanked 0 Times in 0 Posts Trig Identity HELLLLLP! lol i've tried for soo long now. I'm still getting used to these things...they're just like a PUZZLE! thanks! Advertisement     #2   January 21st, 2009, 04:34 PM o_O Primero Espada   Join Date: Mar 2008 Location: Canada Posts: 1,426 Country: Thanks: 150 Thanked 753 Times in 679 Posts This looks awfully familiar to this identity: Let and and the conclusion follows. __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. o_O!?!   #3   January 21st, 2009, 04:38 PM mollymcf2009 Senior Member   Join Date: Jan 2009 Location: Charleston, SC Posts: 490 Country: Thanks: 160 Thanked 118 Times in 114 Posts Do you just need to simplify this using trig identities? Not sure what your question is.   #4   January 21st, 2009, 04:54 PM DaCoo911 Newbie   Join Date: Jan 2009 Posts: 14 Country: Thanks: 6 Thanked 0 Times in 0 Posts ya its just a matter of expanding the left side and simplyfiying down to tanx, i just can't find a way to do it.   #5   January 21st, 2009, 10:37 PM mr fantastic Flow Master   Join Date: Dec 2007 Location: Zeitgeist Posts: 13,510 Country: Thanks: 2,979 Thanked 5,256 Times in 4,605 Posts Quote: Originally Posted by DaCoo911 ya its just a matter of expanding the left side and simplyfiying down to tanx, i just can't find a way to do it. Post #2 tells you exactly how to do it. If you're still stuck please say where. __________________ There are two things you should never try to prove: the impossible and the obvious. The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low and achieving our mark. (Michelangelo Buonarroti) To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.   #6   January 22nd, 2009, 03:09 PM skeeter MHF Contributor   Join Date: Jun 2008 Location: North Texas Posts: 6,247 Country: Thanks: 52 Thanked 2,679 Times in 2,530 Posts hint ... Last edited by mr fantastic; January 22nd, 2009 at 07:07 PM. Reason: No edit - just flagging the reply as having been moved from a duplicate post. The following users thank skeeter for this useful post: Jhevon   #7   January 22nd, 2009, 03:13 PM Jhevon vs Jhevon   Join Date: Feb 2007 Location: New York, USA Posts: 11,590 Country: Thanks: 2,668 Thanked 4,470 Times in 4,155 Posts Quote: Originally Posted by DaCoo911 I have this identity in which i have to prove. Its supposed to be done by means of expanding the left side using sum and difference formulas and then simplifying down to tan x. Just can;t seem to figure it out. Thanks recall, apply this to the left hand side, then multiply the resulting expression by . can you take it from there? __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. " border="0" /> Join the dark side. We have cookies. Threads I link people to too often to have to be looking them up every time: To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. Last edited by mr fantastic; January 22nd, 2009 at 07:07 PM. Reason: No edit - just flagging the reply as having been moved from a duplicate post.   #8   January 22nd, 2009, 03:16 PM DaCoo911 Newbie   Join Date: Jan 2009 Posts: 14 Country: Thanks: 6 Thanked 0 Times in 0 Posts yes that makes sense! thanks both of you for your help! 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