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SAI International School

CLASS – VI

Mathematics

Chapter-14: Practical Geometry-3
Lesson Notes – 3

SUBTOPICS:
1) Perpendiculars
Two lines (or rays or segments) are said to be perpendicular if they intersect such that
the angles formed between them are right angles. In the figure, the lines l and m are
perpendicular.
2) Perpendicular to a line through a point on it
Method-1: Drawing perpendicular using ruler and a set-square
Step 1 A line l and a point P are given. Note that P is on the line l.

Step 2 Place a ruler with one of its edges along l. Hold this firmly.

Step 3 Place a set-square with one of its edges along the already aligned edge of the
ruler such that the right angled corner is in contact with the ruler.

Step 4 Slide the set-square along the edge of ruler until its right angled corner coincides
with P.

Method-2: By using ruler and compasses
Step 1: Given a point P on a line l.

Step 2: With P as centre and a convenient radius, construct an arc intersecting the line l
at two points A and B.