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Thread: Sine, cosine and tangent

  1. #1 Sine, cosine and tangent 
    leohopkins
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    Default March 3rd, 2009, 05:32 AM
    Hi guys.....

    As elementary as this may seen to most of you, and once you have picked yourself up from the floor after laughing, i could do with some help understanding sine, cosine and tangent's.

    First question regarding them: Is it only right angled triangles that this applies to?

    Okay next...... I have drawn a right angled triangle where the angle is measured 69 degrees and the hypotenuse is 8.5cm and the opposite is 8cm.

    Now, calculating the Sine manually (Opposite/Hypotenuse) therefore (8/8.5) I get the figure of........

    0.9411764706

    However, when entering 69 degrees into my calculator and using the Sine function, I get a figure of.......

    ^-.1147848138

    Hmmm..... something isnt going quite my way, or I am doing something wrong? any help would be great. Thanks.


    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  3. #2  
    Leszek Luchowski
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    March 3rd, 2009, 09:24 AM
    Your calculator is set to radians instead of degrees.


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  4. #3  
    leohopkins
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    March 3rd, 2009, 04:17 PM
    aaah okay. How many radians are there in a full circle ?

    Can I buy a protractor with radians on them ?
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  5. #4  
    mathman
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    March 3rd, 2009, 05:13 PM
    Circle has 2pi radians. Don't know about protractors.
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  6. #5  
    organic god
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    March 3rd, 2009, 06:19 PM
    the conversion from degrees to radians is quite simple

    rads = (degs*pi)/180
    everything is mathematical.
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  7. #6  
    Harold14370
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    March 3rd, 2009, 06:21 PM
    Your calculator probably has an option to calculate trig function in degrees.
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  8. #7  
    organic god
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    March 3rd, 2009, 06:29 PM
    harold is correct but it is better to become familiar with radians early.

    radians actually have a geometric interpretation where as the degree is an arbritary division of the circle.

    radians are used more often in mathematical text.
    everything is mathematical.
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  9. #8  
    leohopkins
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    March 4th, 2009, 02:21 AM
    Okay thanks guys.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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