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December 10th, 2009, 12:10 PM  #1 
Newbie Joined: Dec 2009 Posts: 2 Thanks: 0  How can solve this simple equation please step by step
A cos 30° + B cos 45° =0 A sin 30° + B sin 45° =147 
December 10th, 2009, 01:15 PM  #2  
Global Moderator Joined: May 2007 Posts: 6,788 Thanks: 708  Re: How can solve this simple equation please step by step Quote:
 
December 10th, 2009, 01:20 PM  #3 
Global Moderator Joined: Dec 2006 Posts: 20,835 Thanks: 2162 
Since cos 45° = sin 45°, subtracting the first equation from the second gives A(sin 30° + cos 30°) = 147. Hence A = 147/(sin 30° + cos 30°) = 147(cos 30°  sin 30°)/(cos²30°  sin²30°) = 147(cos 30°  sin 30°)/cos 60° = 147((?3)/2  1/2)/(1/2) = 147?3  147. From the first equation, B = A cos 30° / cos 45° = (147?3  147)((?3)/2)/(1/?2) = (441?2  147?6)/2. 
December 11th, 2009, 03:44 PM  #4 
Newbie Joined: Dec 2009 Posts: 2 Thanks: 0  Re: How can solve this simple equation please step by step
thanks for help


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