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      Applying constructions to loci problems

      Lesson details

      Learning outcome

      I can apply the rules for constructing angle and line bisectors to loci problems.

      Key learning points

      1. The perpendicular bisector of a line segment divides the line segment into two equal parts
      2. The perpendicular bisector is the same distance from each end point of the line segment
      3. If you only had the two end points, the perpendicular bisector would still be the same distance from each point
      4. The bisector of an angle divides the angle into two equal parts.

      Keywords

      • Bisect - To bisect means to cut or divide an object into two equal parts.

      • Loci - A locus is a set of points that satisfy a given set of conditions. Multiple sets of points are referred to as loci.

      • Equidistant - Points A and B are equidistant from a third point C if the distance AC is equal to the distance BC.

      Common misconception

      Pupils may believe that there is only one point which is equidistant from two points.

      Highlight that forming any isosceles triangle will mean that that the point is equidistant from both points.

      Teacher tip

      If space allows, you may want to consider getting the pupils to place themselves equidistant from two 'cones' or two walls. Alternatively the use of counters can allow pupils to really consider the points in which satisfy the condition.

      Equipment

      Ruler, pair of compasses, pencil

      Licence

      This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0
      except where otherwise stated. See Oak's terms & conditions
      (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

      6 Questions

      Q1.
      A __________ is a set of points that satisfy a given set of conditions.

      arc
      circle
      line
      Correct answer: locus
      ray

      Q2.
      Which diagram shows the locus of points 3 metres or less from point A?

      An image in a quiz
      Diagram a
      Diagram b
      Correct answer: Diagram c
      Diagram d

      Q3.
      Which diagram shows the locus of points more than 3 metres from point A?

      An image in a quiz
      Diagram a
      Correct answer: Diagram b
      Diagram c
      Diagram d

      Q4.
      Which diagram shows the locus of points 6 cm from the line segment AB?

      An image in a quiz
      Diagram a
      Diagram b
      Correct answer: Diagram c
      Diagram d

      Q5.
      Which diagram shows the locus of points less than 6 cm from the line segment AB?

      An image in a quiz
      Diagram a
      Diagram b
      Diagram c
      Correct answer: Diagram d

      Q6.
      Alex stands somewhere in his garden. Alex is less than 5 m from the house and more than 6 m from the tap. He is within 3 m of the tree. Alex is standing in region .

      An image in a quiz
      Correct Answer: E, e

      6 Questions

      Q1.
      Which diagram shows a perpendicular bisector?

      An image in a quiz
      An image in a quiz
      Correct Answer: An image in a quiz
      An image in a quiz

      Q2.
      Alex places two cones, A and B, on the ground. Which of these points are equidistant from A and B?

      An image in a quiz
      a
      Correct answer: c
      f
      Correct answer: g
      h

      Q3.
      Which of these points are closer to TU than they are to ST?

      An image in a quiz
      b
      c
      Correct answer: e
      Correct answer: g
      f

      Q4.
      Jacob wants to find all the points that are the same distance from LM as they are from MN. What construction should he use?

      An image in a quiz
      The arc of a circle centred on M.
      The perpendicular bisector of LM
      The perpendicular bisector of MN
      The perpendicular bisectors of MN and LM
      Correct answer: The angle bisector of ∠LMN

      Q5.
      Which region is illustrated on this diagram?

      An image in a quiz
      The region of points that are closer to A than to B.
      The region of points that are closer to B than to A.
      Correct answer: The region of points that are equidistant from A and B or closer to A than to B.
      The region of points that are equidistant from A and B or closer to B than to B.

      Q6.
      Select the region which matches this description: closer to AB than BC and closer to CD than AD .

      An image in a quiz
      An image in a quiz
      Correct Answer: An image in a quiz
      An image in a quiz
      An image in a quiz

      To help you plan your 11 maths lesson on: Applying constructions to loci problems, download all teaching resources for free and adapt to suit your pupils' needs...