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  1. #1
    GregoryNeal is offline Member
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    Default Math.atan --- To Degrees Help

    Hi, I've hit a snag. I've got this rather long piece of code that I'm working on, here's the issue area
    Java Code:
    else {
    
    					//input number of sides and side length
    				    int n = Integer.parseInt(d); //number of sides
    
    					String Ss = JOptionPane.showInputDialog(null, "Enter the length of the side: ", n + "-GON", JOptionPane.QUESTION_MESSAGE);
    					double s = Double.parseDouble(Ss); //side length
    
    					//calculate area and perimeter ----begin problem area
    					double deg = (Math.toDegrees(180 / n)); //converts radians to degrees
    					double part = Math.atan(deg); //part is a part of the equation that deals with the tangent of some angle (180/n)
    					TotalArea = (((s * s) * n)/ (4 * (part)));
    
    				System.out.println(TotalArea); //----end problem area
    
    				}
    I'm trying to convert (180/n) to degrees and then take the tangent of it for use in the equation TotalArea. I've been at it for a solid 30 minutes and just can't get it to work. I'm new to java and this is my first time using any of the Math methods (besides Math.pow). The double "TotalArea" has already been predefined earlier, as well as the String "d".
    The program compiles without error, i'm just getting the wrong output.

    ps. the code is to calculate the area of an N-sided regular polygon where s is the side length and n is the number of sides, if that helps.

    Thanks in advance!

  2. #2
    pbrockway2 is offline Moderator
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    Default Re: Math.atan --- To Degrees Help

    the code is to calculate the area of an N-sided regular polygon where s is the side length and n is the number of sides
    That would mean that 180/n is twice the angle subtended at the centre by a side in degrees. If you want to find its tangent you would convert it to radians.

    Also notice that atan() finds the arctangent (aka inverse tangent - it finds an angle whose tangent is equal to the argument). The comment in the code would indicate you want Math.tan(). But trigonometry would indicate that Math.sin() would be more useful.
    Last edited by pbrockway2; 03-07-2012 at 07:58 AM.

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