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Homework Help: Rotation of Regular Polygon

  1. Aug 13, 2009 #1
    1. The problem statement, all variables and given/known data
    A floor tile has the shape of a regular polygon. If the tile is removed from the floor
    and rotated through 50◦ it will fit back exactly into its original place in the floor.
    The least number of sides that the polygon can have is?

    I dont know what are the theories that i should be learning to solve this question.

    One of the Roman dice in the British Museum has 6 square faces and 8 triangular
    faces. It is twice as likely to land on any given square face as any given triangular
    face. What is the probability that the face it lands on is triangular, when thrown?

    I dont understand what the question requires

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Aug 13, 2009 #2


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    Homework Helper

    For the first one, if the polygon is rotated by 50o and is symetrically the same to fit back into the tile space, it means that the least possible sides must be [tex]\frac{360}{50}=7\frac{1}{5}[/tex] sides. But it has to be a polygon, thus the answer needs to be an integer. What highest common factor of 50 is also a factor of 360? What does this tell you?

    For the second, if a square face is twice as likely as a triangle face, can't you then consider 1 square to = 2 triangles? :smile:
  4. Aug 13, 2009 #3
    1)HCF of 360 and 50 is 1800
    Therefore the sides of the polygon is 1800/50=36
    2)The probability is 8/(6*2+8)=2/5

    Can you please prompt me on this question?
    If f(x)=[tex]a_0+a_1x+a_2x^2 ... a_nx^n[/tex]

    Find f(7)
  5. Aug 13, 2009 #4


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    Homework Helper

    well you actually found the lowest common denominator of both numbers, but you adjusted your last part to the problem to get the correct answer :smile:
    Another way, the highest common factor would be 10o (10 is the largest number that can be multiplied by an integer to become both 50 and 360) and thus the sides of the polygon is 360o/10o=36 sides.

    Yes you correctly found the probability.

    Sorry I'm unsure of the answer myself. You should create another thread for it.
  6. Aug 13, 2009 #5
    You've been a great help , Thanks! :smile:
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