Topic/Skill
Topic: Loci Definition/Tips
and Constructions Example
1. Parallel Parallel lines never meet.
2. Perpendicular lines are at right angles.
Perpendicular There is a 90° angle between them.
3. Vertex A corner or a point where two lines meet.
4. Angle Angle Bisector: Cuts the angle in half.
Bisector
1. Place the sharp end of a pair of
compasses on the vertex.
2. Draw an arc, marking a point on each
line.
3. Without changing the compass put the
compass on each point and mark a centre
point where two arcs cross over.
4. Use a ruler to draw a line through the
vertex and centre point.
5. Perpendicular Bisector: Cuts a line in
Perpendicular half and at right angles.
Bisector
1. Put the sharp point of a pair of
compasses on A.
2. Open the compass over half way on the
line.
3. Draw an arc above and below the line.
4. Without changing the compass, repeat
from point B.
5. Draw a straight line through the two
intersecting arcs.
6. The perpendicular distance from a point
Perpendicular to a line is the shortest distance to that
from an line.
External Point
1. Put the sharp point of a pair of
compasses on the point.
2. Draw an arc that crosses the line twice.
3. Place the sharp point of the compass on
one of these points, open over half way and
draw an arc above and below the line.
4. Repeat from the other point on the line.
5. Draw a straight line through the two
Mr A. Coleman Glyn School
Topic: Loci Definition/Tips
and Constructions Example
1. Parallel Parallel lines never meet.
2. Perpendicular lines are at right angles.
Perpendicular There is a 90° angle between them.
3. Vertex A corner or a point where two lines meet.
4. Angle Angle Bisector: Cuts the angle in half.
Bisector
1. Place the sharp end of a pair of
compasses on the vertex.
2. Draw an arc, marking a point on each
line.
3. Without changing the compass put the
compass on each point and mark a centre
point where two arcs cross over.
4. Use a ruler to draw a line through the
vertex and centre point.
5. Perpendicular Bisector: Cuts a line in
Perpendicular half and at right angles.
Bisector
1. Put the sharp point of a pair of
compasses on A.
2. Open the compass over half way on the
line.
3. Draw an arc above and below the line.
4. Without changing the compass, repeat
from point B.
5. Draw a straight line through the two
intersecting arcs.
6. The perpendicular distance from a point
Perpendicular to a line is the shortest distance to that
from an line.
External Point
1. Put the sharp point of a pair of
compasses on the point.
2. Draw an arc that crosses the line twice.
3. Place the sharp point of the compass on
one of these points, open over half way and
draw an arc above and below the line.
4. Repeat from the other point on the line.
5. Draw a straight line through the two
Mr A. Coleman Glyn School
