Shapes and their names Cambridge IGCSE Mathematics revision

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In plain words

Geometry has its own vocabulary, and questions use it without explaining. Know the names of the triangles, the four-sided shapes, the parts of a circle and the common solids, and what makes each one special.

Three things to know

  1. Triangles: equilateral (all sides equal), isosceles (two equal), scalene (none equal), right-angled. Quadrilaterals: square, rectangle, parallelogram, rhombus, trapezium (one pair of parallel sides), kite.
  2. Circle: the radius goes from the centre to the edge; the diameter goes right across through the centre; a chord joins two points on the edge; a tangent touches the circle once; an arc is part of the edge; a sector is a "pizza slice".
  3. Solids have faces, edges and vertices (corners). A cuboid has 6 faces, 12 edges and 8 vertices. A net is a solid folded out flat.

Tips and tricks

  • A rhombus has four equal sides; a parallelogram has two pairs of equal sides. Every square is a rhombus and a rectangle.
  • Diameter = 2 × radius. Read carefully which one the question gives you.
5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Shapes and their names: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

  1. Which triangle has exactly two equal sides?
    • equilateral
    • isosceles (the answer)
    • scalene
    • right-angled

    It also has two equal angles.

  2. What is a line from the centre of a circle to its edge called?
    • diameter
    • chord
    • radius (the answer)
    • tangent

    The diameter is twice as long.

  3. How many edges does a cuboid have?
    • 6
    • 8
    • 12 (the answer)
    • 24

    Four on top, four on the bottom, four upright.

  4. Which quadrilateral has four equal sides and four right angles?
    • rectangle
    • rhombus
    • square (the answer)
    • kite

    A rhombus has equal sides but not right angles.

  5. What is a sector of a circle?
    • a straight line across it
    • a "slice" between two radii (the answer)
    • the whole edge
    • half the circle only

    It is bounded by two radii and an arc.

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