Visualising and representing

  • On Time
    problem

    On Time

    Age
    11 to 14
    Challenge level
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    On a clock the three hands - the second, minute and hour hands - are on the same axis. How often in a 24 hour day will the second hand be parallel to either of the two other hands?
  • Trice
    problem

    Trice

    Age
    11 to 14
    Challenge level
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    ABCDEFGH is a 3 by 3 by 3 cube. Point P is 1/3 along AB (that is AP : PB = 1 : 2), point Q is 1/3 along GH and point R is 1/3 along ED. What is the area of the triangle PQR?
  • Linkage
    problem

    Linkage

    Age
    11 to 14
    Challenge level
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    Four rods, two of length a and two of length b, are linked to form a kite. The linkage is moveable so that the angles change. What is the maximum area of the kite?
  • Rolling Triangle
    problem

    Rolling Triangle

    Age
    11 to 14
    Challenge level
    filled star filled star filled star
    The triangle ABC is equilateral. The arc AB has centre C, the arc BC has centre A and the arc CA has centre B. Explain how and why this shape can roll along between two parallel tracks.
  • Around and Back
    problem

    Around and Back

    Age
    14 to 16
    Challenge level
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    A cyclist and a runner start off simultaneously around a race track each going at a constant speed. The cyclist goes all the way around and then catches up with the runner. He then instantly turns around and heads back to the starting point where he meets the runner who is just finishing his first circuit. Find the ratio of their speeds.
  • Take Ten
    problem

    Take Ten

    Age
    11 to 14
    Challenge level
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    Is it possible to remove ten unit cubes from a 3 by 3 by 3 cube so that the surface area of the remaining solid is the same as the surface area of the original?
  • Getting an angle
    problem

    Getting an Angle

    Age
    11 to 14
    Challenge level
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    How can you make an angle of 60 degrees by folding a sheet of paper twice?
  • Cutting a Cube
    problem

    Cutting a Cube

    Age
    11 to 14
    Challenge level
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    A half-cube is cut into two pieces by a plane through the long diagonal and at right angles to it. Can you draw a net of these pieces? Are they identical?
  • Cubic Conundrum
    problem

    Cubic Conundrum

    Age
    7 to 16
    Challenge level
    filled star filled star filled star
    Which of the following cubes can be made from these nets?
  • Rati-o
    problem

    Rati-O

    Age
    11 to 14
    Challenge level
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    Points P, Q, R and S each divide the sides AB, BC, CD and DA respectively in the ratio of 2 : 1. Join the points. What is the area of the parallelogram PQRS in relation to the original rectangle?