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BASiCS of GeoMetRy

The word geometry is derived from the Greek words ‘geo’ meaning ‘Earth’ and ‘metro’
meaning ‘measurement’. Thus, the word ‘geometry’ means “Earth’s measurement”.
Let us go through some basics of geometry.

Basics of Geometry

Point A point shows an exact position or
place. It looks like a dot. It has no length,
breadth, or height. It is denoted by a
capital letter, like Point A, Point B, Point
C.

Line A line is straight and goes on for ever in
both directions. It has no endpoints. A
line AB shown in the adjoining figure is
denoted by AB or line m.

Line segment A part of a line with two endpoints is
called a line segment. A line segment
AB shown in the adjoining figure is
denoted by AB or BA.

Ray A part of a line with one endpoint is
called a ray. It goes on endlessly in
one direction. A ray AB shown in the
adjoining figure is denoted by AB ,
where A is its initial point.

Measuring a line Segment

We use a centimetre ruler (scale) to measure line segments. The length between two
consecutive numbers on this scale is 1 cm.

FP

example 1. Measure the given line segment using a scale.
A 7 cm B

Solution. FP

Step 1. Place the scale along the line segment in such a way that one end of the line
segment coincides with the zero mark on the scale.

A 7 cm B
FP

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Geometry