Perimeter

  • Five circuits, seven spins
    problem

    Five circuits, seven spins

    Age
    16 to 18
    Challenge level
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    A circular plate rolls inside a rectangular tray making five circuits and rotating about its centre seven times. Find the dimensions of the tray.
  • Coins on a Plate
    problem

    Coins on a plate

    Age
    11 to 14
    Challenge level
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    Points A, B and C are the centres of three circles, each one of which touches the other two. Prove that the perimeter of the triangle ABC is equal to the diameter of the largest circle.
  • Is there a theorem?
    problem

    Is there a theorem?

    Age
    11 to 14
    Challenge level
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    Draw a square. A second square of the same size slides around the first always maintaining contact and keeping the same orientation. How far does the dot travel?
  • Contact
    problem

    Contact

    Age
    14 to 16
    Challenge level
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    A circular plate rolls in contact with the sides of a rectangular tray. How much of its circumference comes into contact with the sides of the tray when it rolls around one circuit?
  • Coke machine
    problem

    Coke machine

    Age
    14 to 16
    Challenge level
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    The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design...
  • Some(?) of the Parts
    problem

    Some(?) of the parts

    Age
    14 to 16
    Challenge level
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    A circle touches the lines OA, OB and AB where OA and OB are perpendicular. Show that the diameter of the circle is equal to the perimeter of the triangle
  • Lawn Border
    problem

    Lawn border

    Age
    5 to 11
    Challenge level
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    If I use 12 green tiles to represent my lawn, how many different ways could I arrange them? How many border tiles would I need each time?
  • Fencing Lambs
    problem

    Fencing lambs

    Age
    7 to 11
    Challenge level
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    A thoughtful shepherd used bales of straw to protect the area around his lambs. Explore how you can arrange the bales.