Similarity and congruence

  • Building Up
    problem

    Triangular Slope

    Age
    14 to 16
    Challenge level
    filled star filled star filled star

    Can you find the gradients of the lines that form a triangle?

  • From all corners
    problem

    From All Corners

    Age
    14 to 16
    Challenge level
    filled star filled star filled star

    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.

  • Points in Pairs
    problem

    Points in Pairs

    Age
    14 to 16
    Challenge level
    filled star filled star filled star

    Move the point P to see how P' moves. Then use your insights to calculate a missing length.

  • Wedge on Wedge
    problem

    Wedge on Wedge

    Age
    14 to 16
    Challenge level
    filled star filled star filled star

    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?

  • Pentakite
    problem

    Pentakite

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

    Given a regular pentagon, can you find the distance between two non-adjacent vertices?

  • Stadium Sightline
    problem

    Stadium Sightline

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

    How would you design the tiering of seats in a stadium so that all spectators have a good view?

  • Pent
    problem

    Pent

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

    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.

  • Chord
    problem

    Chord

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

    Equal touching circles have centres on a line. From a point of this line on a circle, a tangent is drawn to the farthest circle. Find the lengths of chords where the line cuts the other circles.

  • Another Triangle in a Triangle
    problem

    Another Triangle in a Triangle

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

    Can you work out the fraction of the original triangle that is covered by the green triangle?