March 4th, 2011, 08:50 PM  #1 
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0  Trigonometry 
March 4th, 2011, 09:51 PM  #2 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,206 Thanks: 513 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, 10:01 PM  #3  
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0  Quote:
Quote:
 
March 4th, 2011, 10:18 PM  #4 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,206 Thanks: 513 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, 10:32 PM  #5  
Senior Member Joined: Apr 2007 Posts: 2,140 Thanks: 0  Quote:
My textbook's answer.  
March 7th, 2011, 05:04 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 19,952 Thanks: 1842 
In that case, your textbook's answer is incorrect, since it omits some solutions.

March 7th, 2011, 02:06 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!


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