Explaining, convincing and proving

  • Rational Round
    problem

    Rational Round

    Age
    16 to 18
    Challenge level
    3 out of 3

    Show that there are infinitely many rational points on the unit circle and no rational points on the circle x^2+y^2=3.

  • Modular Fractions
    problem

    Modular Fractions

    Age
    16 to 18
    Challenge level
    3 out of 3

    We only need 7 numbers for modulus (or clock) arithmetic mod 7 including working with fractions. Explore how to divide numbers and write fractions in modulus arithemtic.

  • Poly Fibs
    problem

    Poly Fibs

    Age
    16 to 18
    Challenge level
    3 out of 3

    A sequence of polynomials starts 0, 1 and each poly is given by combining the two polys in the sequence just before it. Investigate and prove results about the roots of the polys.

  • Water Pistols
    problem

    Water Pistols

    Age
    16 to 18
    Challenge level
    3 out of 3

    With n people anywhere in a field each shoots a water pistol at the nearest person. In general who gets wet? What difference does it make if n is odd or even?

  • Thousand Words
    problem

    Thousand Words

    Age
    16 to 18
    Challenge level
    3 out of 3

    Here the diagram says it all. Can you find the diagram?

  • Cyclic Triangles
    problem

    Cyclic Triangles

    Age
    16 to 18
    Challenge level
    3 out of 3

    Make and prove a conjecture about the cyclic quadrilateral inscribed in a circle of radius r that has the maximum perimeter and the maximum area.

  • Plus or Minus
    problem

    Plus or Minus

    Age
    16 to 18
    Challenge level
    3 out of 3

    Make and prove a conjecture about the value of the product of the Fibonacci numbers $F_{n+1}F_{n-1}$.

  • Integral Inequality
    problem

    Integral Inequality

    Age
    16 to 18
    Challenge level
    3 out of 3

    An inequality involving integrals of squares of functions.

  • Proof of Pick's Theorem
    problem

    Proof of Pick's Theorem

    Age
    16 to 18
    Challenge level
    3 out of 3

    Follow the hints and prove Pick's Theorem.

  • Rarity
    problem

    Rarity

    Age
    16 to 18
    Challenge level
    3 out of 3

    Show that it is rare for a ratio of ratios to be rational.