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    (Original post by User23)
    Radians?
    All I did was just do x/360 x 12 pi = 14.5929....
    Then I made x the subject of the formula
    OK, if you've not come across radians.

    Circumference is 2*pi*r, or pi*d

    And multiply by x/360 for the arc length subtending an angle of x degrees.

    You've used pi*r.

    You're missing a factor of 2.
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    (Original post by ghostwalker)
    OK, if you've not come across radians.

    Circumference is 2*pi*r, or pi*d

    And multiply by x/360 for the arc length subtending an angle of x degrees.

    You've used pi*r.

    You're missing a factor of 2.

    Oh so is the answer 84 degrees???
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    (Original post by User23)
    Oh so is the answer 84 degrees???
    That's what I make it.
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    (Original post by User23)
    Oh so is the answer 84 degrees???
    Can't be 84 degrees if the diagram is correct, because it looks like angle x is bigger than 90 degrees.

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    (Original post by Ishan_2000)
    Can't be 84 degrees if the diagram is correct, because it looks like angle x is bigger than 90 degrees.

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    I don't think the diagram is drawn to scale though.
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    (Original post by Ishan_2000)
    Can't be 84 degrees if the diagram is correct, because it looks like angle x is bigger than 90 degrees.

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    As User23 said, diagrams aren't always accurate. Diagram is actually misleading.

    You could make a model if you want an additional check.
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    (Original post by ghostwalker)
    As User23 said, diagrams aren't always accurate. Diagram is actually misleading.

    You could make a model if you want an additional check.
    I guess diagrams aren't always correct, as User23 said.
    But, they must be or should be vaguely correct. Maybe just an awful diagram.
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    I used a different approach and got the same answer, it's easier to use the methods above though.

    Arc length = 5.6 * pi
    Area of sector = 0.5 * arc length * radius = 0.5 * arc length * 12

    Area of sector = x/360 * (pi * r^2)
    x = 360A / pi * r^2)
    x = 360A / 144 pi


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Updated: October 28, 2015
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