Area - triangles, quadrilaterals, compound shapes

  • Square pizza
    problem

    Square pizza

    Age
    14 to 16
    Challenge level
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    Can you show that you can share a square pizza equally between two people by cutting it four times using vertical, horizontal and diagonal cuts through any point inside the square?
  • Rhombus in Rectangle
    problem

    Rhombus in rectangle

    Age
    14 to 16
    Challenge level
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    Take any rectangle ABCD such that AB > BC. The point P is on AB and Q is on CD. Show that there is exactly one position of P and Q such that APCQ is a rhombus.
  • Of all the areas
    problem

    Of all the areas

    Age
    14 to 16
    Challenge level
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    Can you find a general rule for finding the areas of equilateral triangles drawn on an isometric grid?

  • 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?
  • Isosceles
    problem

    Isosceles

    Age
    11 to 14
    Challenge level
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    Prove that a triangle with sides of length 5, 5 and 6 has the same area as a triangle with sides of length 5, 5 and 8. Find other pairs of non-congruent isosceles triangles which have equal areas.
  • Same Height
    problem

    Same height

    Age
    14 to 16
    Challenge level
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    A trapezium is divided into four triangles by its diagonals. Can you work out the area of the trapezium?
  • Arrowhead
    problem

    Arrowhead

    Age
    14 to 16
    Challenge level
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    The points P, Q, R and S are the midpoints of the edges of a non-convex quadrilateral.What do you notice about the quadrilateral PQRS and its area?
  • Quad in Quad
    problem

    Quad in quad

    Age
    14 to 18
    Challenge level
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    Join the midpoints of a quadrilateral to get a new quadrilateral. What is special about it?

  • From all corners
    problem

    From all corners

    Age
    14 to 16
    Challenge level
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    Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.
  • Kissing Triangles
    problem

    Kissing triangles

    Age
    11 to 14
    Challenge level
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    Determine the total shaded area of the 'kissing triangles'.