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January 13th, 2009, 03:50 AM  #1 
Newbie Joined: Jan 2009 Posts: 7 Thanks: 0  Trigonometry Angle help
Hi, Im assusmin skipjack would be the first to ansear I have had some question on trig and i could easily find the lines like e.g. whats the size of AB However when im doing this i either have to do SIN the angle ,TAN thhe angle,COS the angle. But what happens if there is no angle. This is what i do.. Firstly lets say the angle is called "alpha" and we are using tangent aand opposite, so we use TAN next i did is TAN "alpha" = lets say the sides are 6 which is the opposite and 3 the tangent all i did was TAN "alpha" = 6/3 Now i did this on my calculator. INVERSE TAN 3 iam shure i did everythign correct apart from last part so can someone explain please. Thank you. 
January 13th, 2009, 10:03 AM  #2 
Newbie Joined: Jan 2009 Posts: 7 Thanks: 0  Re: Trigonometry Angle help
really appreciate if someone could tell me

January 13th, 2009, 10:28 AM  #3 
Newbie Joined: Aug 2008 Posts: 4 Thanks: 0  Re: Trigonometry Angle help
I didn't quite get what the problem was, but I'll take an uncivilized chance.. tan(A) = opposite / adjacent opposite = 6 adjacent = 3 tan(A) = (6/3) A = ArcTan (6/3) A ? 63,4° 
January 13th, 2009, 12:12 PM  #4 
Global Moderator Joined: Dec 2006 Posts: 20,484 Thanks: 2041 
If "there is no angle", you cannot proceed to say what the angle is called! Also, if there is indeed an angle, and its tangent is 3, your calculator will have given you the value of the angle (to within a multiple of pi). If the tangent, 3, was calculated as opposite/adjacent, you know that the opposite side is three times the adjacent side. 
January 14th, 2009, 03:52 AM  #5 
Newbie Joined: Jan 2009 Posts: 7 Thanks: 0  Re: Trigonometry Angle help
thanks i understand it now

January 16th, 2009, 12:08 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 20,484 Thanks: 2041 
If the opposite is 6 and the adjacent is 3, the tangent is 2. You can find atan(2) (or atan of any other value) using Google calculator (or any scientific calculator).


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