Reflections

  • Tricircle
    problem

    Tricircle

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    The centre of the larger circle is at the midpoint of one side of an equilateral triangle and the circle touches the other two sides of the triangle. A smaller circle touches the larger circle and two sides of the triangle. If the small circle has radius 1 unit find the radius of the larger circle.
  • Snookered
    problem

    Snookered

    Age
    14 to 18
    Challenge level
    filled star filled star empty star
    In a snooker game the brown ball was on the lip of the pocket but it could not be hit directly as the black ball was in the way. How could it be potted by playing the white ball off a cushion?
  • Two triangles in a Square
    problem

    Two triangles in a square

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    Given that ABCD is a square, M is the mid point of AD and CP is perpendicular to MB with P on MB, prove DP = DC.
  • Screen Shot
    problem

    Screen shot

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    A moveable screen slides along a mirrored corridor towards a centrally placed light source. A ray of light from that source is directed towards a wall of the corridor, which it strikes at 45 degrees before being reflected across to the opposite wall and so on until it hits the screen.
  • Footprints
    problem

    Footprints

    Age
    16 to 18
    Challenge level
    filled star filled star empty star
    Make a footprint pattern using only reflections.
  • One Reflection Implies Another
    problem

    One reflection implies another

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    When a strip has vertical symmetry there always seems to be a second place where a mirror line could go. Perhaps you can find a design that has only one mirror line across it. Or, if you thought that was impossible, could you explain why ?
  • Combining Transformations
    problem

    Combining transformations

    Age
    11 to 14
    Challenge level
    filled star filled star empty star
    Does changing the order of transformations always/sometimes/never produce the same transformation?
  • The Fire-fighter's Car Keys
    problem

    The fire-fighter's car keys

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    A fire-fighter needs to fill a bucket of water from the river and take it to a fire. What is the best point on the river bank for the fire-fighter to fill the bucket ?.
  • Semaphore
    problem

    Semaphore

    Age
    11 to 14
    Challenge level
    filled star filled star empty star
    I am standing behind five pupils who are signalling a five-digit number to someone on the opposite side of the playground. What number is actually being signalled?
  • Reading from Behind
    problem

    Reading from behind

    Age
    11 to 14
    Challenge level
    filled star filled star empty star
    Can you find the time between 3 o'clock and 10 o'clock when my digital clock looks the same from both the front and back?