Golden ratio

  • Gold Yet Again
    problem

    Gold yet again

    Age
    16 to 18
    Challenge level
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    Nick Lord says "This problem encapsulates for me the best features of the NRICH collection."
  • Golden Fractions
    problem

    Golden fractions

    Age
    16 to 18
    Challenge level
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    Find the link between a sequence of continued fractions and the ratio of succesive Fibonacci numbers.
  • Golden Fibs
    problem

    Golden fibs

    Age
    16 to 18
    Challenge level
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    When is a Fibonacci sequence also a geometric sequence? When the ratio of successive terms is the golden ratio!
  • Pentakite
    problem

    Pentakite

    Age
    14 to 18
    Challenge level
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    Given a regular pentagon, can you find the distance between two non-adjacent vertices?
  • Golden Ratio
    problem

    Golden ratio

    Age
    16 to 18
    Challenge level
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    Solve an equation involving the Golden Ratio phi where the unknown occurs as a power of phi.
  • Pent
    problem

    Pent

    Age
    14 to 18
    Challenge level
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    The diagram shows a regular pentagon with sides of unit length. Find all the angles in the diagram. Prove that the quadrilateral shown in red is a rhombus.
  • Golden Powers
    problem

    Golden powers

    Age
    16 to 18
    Challenge level
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    You add 1 to the golden ratio to get its square. How do you find higher powers?
  • Darts and Kites
    problem

    Darts and kites

    Age
    14 to 16
    Challenge level
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    Explore the geometry of these dart and kite shapes!
  • Golden Triangle
    problem

    Golden triangle

    Age
    16 to 18
    Challenge level
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    Three triangles ABC, CBD and ABD (where D is a point on AC) are all isosceles. Find all the angles. Prove that the ratio of AB to BC is equal to the golden ratio.
  • Pythagorean Golden Means
    problem

    Pythagorean golden means

    Age
    16 to 18
    Challenge level
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    Show that the arithmetic mean, geometric mean and harmonic mean of a and b can be the lengths of the sides of a right-angles triangle if and only if a = bx^3, where x is the Golden Ratio.