3.2 Constructions and loci
Constructions and loci
Everything on constructions and loci that can come up in the WJEC GCSE Mathematics and Numeracy, in Unit 2 and Unit 3. Each skill below has the method, the mistake that costs the most marks, a worked example, and free practice marked the way WJEC marks it.
Practise constructions and loci free
A worked example
Loci · [1 mark]
Which describes this locus? Points that are exactly 2 cm from a straight line (of endless length).
- B1Two lines parallel to it, 2 cm either side
The exam skills (2)
Loci
- Same distance from two points: the perpendicular bisector of the line joining them.
- Same distance from two lines: the angle bisector.
- Fixed distance from a point: a circle.
Watch out: Mixing up the perpendicular bisector and the angle bisector.
Constructions
- Use compasses and keep the radius the same for matching arcs.
- Leave all your construction arcs on the drawing.
- Draw neatly with a sharp pencil and a ruler.
Watch out: Rubbing out the arcs. They are the evidence you constructed it.
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