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Homework Help: Interior and Exterior Angle of a Polygon: Formula not working

  1. Dec 1, 2017 #1
    1. The problem statement, all variables and given/known data
    How many sides does a polygon have if the measure of each interior angle is 8 times the measure of each exterior angle?

    2. Relevant equations
    Interior angle of a polygon: ((n-2) * 180)/n
    Exterior angle of a polygon: (360)/n

    3. The attempt at a solution
    ((n-2) * 180)/n = 8 * (360)/n
    now ((n-2) * 180) = 8 * 360
    180 n -360 = 8 * 360
    180 n = 7 * 360
    n = 14
    I am getting n = 14 which is wrong.

    Some body please guide me what is the problem.

  2. jcsd
  3. Dec 1, 2017 #2


    Staff: Mentor

    Work is fine to here, but you have a mistake in the line below. Two lines above, it would be simpler to divide both sides by 180, to get simpler numbers to work with.
    Alternatively, in the line above, you are adding 360 to both sides of the equation.
  4. Dec 1, 2017 #3


    User Avatar
    Science Advisor
    Gold Member

    Check the math

    EDIT: beaten for some seconds by Mark44
    Last edited: Dec 1, 2017
  5. Dec 1, 2017 #4
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