Constructions and loci · Year 8
In Year 8 you learn: perpendicular bisectors and angle bisectors.
Constructions are accurate drawings made with a ruler and compasses only. A locus (plural loci) is the set of all points that follow a rule, such as “3 m from a post” or “the same distance from two points”, and is drawn with the same constructions.
Key facts
- Perpendicular bisector of AB: equal arcs from A and B; join the crossings. Its points are equidistant from A and B.
- Angle bisector: an arc from the corner cuts both arms; equal arcs from those points cross on the bisector.
- Triangle from three sides: draw one side, then arcs of the other two lengths from its ends.
- A fixed distance from a line makes parallel lines (with semicircles round the ends of a line segment).
- Leave construction arcs showing: they are your working.