March 4th, 2011, 07:50 PM  #1 
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0  Trigonometry 
March 4th, 2011, 08:51 PM  #2 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Trigonometry
1) Apply the doubleangle identities for sine and cosine: Divide through by 2: Factor by grouping: 2) Set first factor equal to zero: Apply linear combination identity: Setting yields for the interval given: Set second factor equal to zero: Apply linear combination identity: Setting and yields for the given interval: 
March 4th, 2011, 09:01 PM  #3  
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0  Quote:
Quote:
 
March 4th, 2011, 09:18 PM  #4 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Trigonometry
For problem 2, I should have put all the solutions together: For problem 1, with no restriction on x, we could write the solutions for the two factors as: 
March 4th, 2011, 09:32 PM  #5  
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0  Quote:
My textbook's answer.  
March 7th, 2011, 04:04 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 20,654 Thanks: 2087 
In that case, your textbook's answer is incorrect, since it omits some solutions.

March 7th, 2011, 01:06 PM  #7 
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0 
I knew you were smarter than my textbook's solutions! Thanks for letting me know!


Tags 
trigonometry 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Trigonometry  alloy  Trigonometry  2  October 10th, 2012 02:51 AM 
HELP :::::: trigonometry PLEASE  hgphtgi  Trigonometry  3  October 1st, 2012 10:27 AM 
Trigonometry  yeoky  Trigonometry  2  September 27th, 2012 07:04 PM 
Trigonometry  Rekooo  Algebra  6  December 13th, 2010 03:13 PM 
Trigonometry!!  puremath  Algebra  4  May 30th, 2010 12:26 PM 