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Math Help - Easy Easy Trig help

  1. #1
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    Easy Easy Trig help

    A cone is 15cm high and has a semi-vertical angle of 18 degrees.

    I'm quite good at trigonometry but I just don't get this question can someone help me?

    Thanks in advance
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  2. #2
    Super Member bigwave's Avatar
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    the semi vertical angle of a cone is the angle
    between the axis and a line in the surface which passes through the apex.
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  3. #3
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    Ok I think I get it. So I have to find the radius

    so if I make a right angled triangle...

     \sin 18 = \frac {x}{15}

     x = 15*\sin 18

     = 4.64

    is this right?
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  4. #4
    Super Member bigwave's Avatar
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    Talking

    Quote Originally Posted by jgv115 View Post
    Ok I think I get it. So I have to find the radius

    so if I make a right angled triangle...

     \sin 18 = \frac {x}{15}

     x = 15*\sin 18

     = 4.64

    is this right?
    seems so...
    don't forget units especially on a test
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