Regular polygons and circles

  • Curvy areas
    problem
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    Curvy Areas

    Age
    14 to 16
    Challenge level
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    Have a go at creating these images based on circles. What do you notice about the areas of the different sections?

  • Circle Packing
    problem

    Circle Packing

    Age
    14 to 16
    Challenge level
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    Equal circles can be arranged so that each circle touches four or six others. What percentage of the plane is covered by circles in each packing pattern? ...

  • Geometry and Measure - Short Problems
    problem

    F'arc'tion

    Age
    14 to 16
    Challenge level
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    At the corner of the cube circular arcs are drawn and the area enclosed shaded. What fraction of the surface area of the cube is shaded? Try working out the answer without recourse to pencil and paper.

  • Semi-detached
    problem
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    Semi-Detached

    Age
    14 to 16
    Challenge level
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    A square of area 40 square cms is inscribed in a semicircle. Find the area of the square that could be inscribed in a circle of the same radius.

  • Polycircles
    problem

    Polycircles

    Age
    14 to 16
    Challenge level
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    Show that for any triangle it is always possible to construct 3 touching circles with centres at the vertices. Is it possible to construct touching circles centred at the vertices of any polygon?

  • The Pillar of Chios
    problem

    The Pillar of Chios

    Age
    14 to 16
    Challenge level
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    Semicircles are drawn on the sides of a rectangle. Prove that the sum of the areas of the four crescents is equal to the area of the rectangle.

  • Crescents and triangles
    problem

    Crescents and Triangles

    Age
    14 to 16
    Challenge level
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    Can you find a relationship between the area of the crescents and the area of the triangle?

  • Partly Circles
    problem
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    Partly Circles

    Age
    14 to 16
    Challenge level
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    What is the same and what is different about these circle questions? What connections can you make?

  • Bicentric Quadrilaterals
    problem

    Bicentric Quadrilaterals

    Age
    14 to 16
    Challenge level
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    Investigate the properties of quadrilaterals which can be drawn with a circle just touching each side and another circle just touching each vertex.
  • Baby Circle
    problem
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    Baby Circle

    Age
    16 to 18
    Challenge level
    filled star empty star empty star

    A small circle fits between two touching circles so that all three circles touch each other and have a common tangent? What is the exact radius of the smallest circle?