Triangles

  • Equal Equilateral Triangles
    problem

    Equal Equilateral Triangles

    Age
    14 to 16
    Challenge level
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    Can you make a regular hexagon from yellow triangles the same size as a regular hexagon made from green triangles ?

  • Pareq Exists
    problem

    Pareq Exists

    Age
    14 to 16
    Challenge level
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    Prove that, given any three parallel lines, an equilateral triangle always exists with one vertex on each of the three lines.

  • Two triangles in a Square
    problem

    Two Triangles in a Square

    Age
    14 to 16
    Challenge level
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    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.

  • Tetrahedra Tester
    problem

    Tetrahedra Tester

    Age
    14 to 16
    Challenge level
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    An irregular tetrahedron is composed of four different triangles. Can such a tetrahedron be constructed where the side lengths are 4, 5, 6, 7, 8 and 9 units of length?

  • The Square Hole
    problem

    The Square Hole

    Age
    14 to 16
    Challenge level
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    If the yellow equilateral triangle is taken as the unit for area, what size is the hole ?
  • Three Way Split
    problem

    Three Way Split

    Age
    14 to 16
    Challenge level
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    Take any point P inside an equilateral triangle. Draw PA, PB and PC from P perpendicular to the sides of the triangle where A, B and C are points on the sides. Prove that PA + PB + PC is a constant.

  • Wedge on Wedge
    problem

    Wedge on Wedge

    Age
    14 to 16
    Challenge level
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    Two right-angled triangles are connected together as part of a structure. An object is dropped from the top of the green triangle where does it pass the base of the blue triangle?

  • Altitude Inequalities
    problem

    Altitude Inequalities

    Age
    14 to 16
    Challenge level
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    Weekly Problem 8 - 2010
    Are you able to find triangles such that these five statements are true?

  • Xtra
    problem

    Xtra

    Age
    14 to 18
    Challenge level
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    Find the sides of an equilateral triangle ABC where a trapezium BCPQ is drawn with BP=CQ=2 , PQ=1 and AP+AQ=sqrt7 . Note: there are 2 possible interpretations.

  • Calculating with cosines
    problem

    Calculating With Cosines

    Age
    14 to 18
    Challenge level
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    If I tell you two sides of a right-angled triangle, you can easily work out the third. But what if the angle between the two sides is not a right angle?