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Year 11 - Maths

Constructing loci

Loci and construction

Unit Summary

In this unit, pupils construct triangles and construct diagrams following specific restrictions using their knowledge of loci and their work on constructions.

Lesson Summary

You will learn to construct a set of points that satisfy a set of conditions.

Key Notes

  • Constructing a set of points a set distance from a given point produces a circle
  • A compass should be used for this construction
  • The point could be the vertex of a shape or contained within a shape
  • A ruler should be used to indicate two points that are a set distance from a line
  • The end points of the line should have a compass used to indicate the distance from the point

Vocabulary To Learn

  • Locus/Loci: A locus is a set of points that satisfy a given set of conditions. Multiple sets of points are referred to as loci.
  • Circle: A circle is a locus of points that are equidistant from a fixed point. This fixed point is the centre of the circle and the distance from the centre to the locus of points is the radius of the circle.

Common Mistakes To Avoid

  • Pupils may think that the locus of a line is a rectangle.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

Constructing a set of points a set distance from a given point produces a circle. A compass should be used for this construction.

2. Use this key word in a maths sentence and explain it clearly. 'Locus/Loci'

A locus is a set of points that satisfy a given set of conditions. Multiple sets of points are referred to as loci. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Pupils may think that the locus of a line is a rectangle. Correction: Choose the vertices of their rectangle and ask if they are the same distance from the line as another point. Link to Pythagoras' theorem if necessary to highlight that the diagonal length will be longer.

More Lessons In This Unit

Browse all guides in the Year 11 Maths guide library.