Page 155 - ICSE Math 6

14 Fundamental Concepts of

Geometry

Key Concepts

• Introduction to Geometry • Interior, Exterior and Boundary of Closed Figures
• Point, Line, Line Segment, Ray, Plane and Space • Curvilinear and Linear Boundaries
• Parallel, Intersecting and Perpendicular Lines • Collinear and Non-collinear Points
• Perpendicular Bisector • Concurrent and Non-concurrent Lines
• Open and Closed Figures

Geometry is a branch of Mathematics which deals with the
study of shape, size and relative position of figures. In ancient
times, people used geometry in several ways which includes
surveying land areas, measuring storage containers, constructing;
palaces, temples, etc. Eventually it was realized that geometry
is not restricted to the study of plane surfaces but it is reflected
in any form of art, measurement, architecture, etc.

Look closely at the photograph of any building like your house, Gateway of India, Mumbai
school or neighbour’s house. You will find that the building has
been built using various concepts of lines and angles. Architects and builders use concepts of lines
and angles to construct buildings, bridges, monuments, etc.
Similarly, a carpenter uses the concept of lines and angles to make furniture. Let’s define some of the
terms which are frequently used in geometry.

Point
A point is a mark of position. A small dot represents a point and it is denoted by a capital A
letter like A, B or C. A point has no length, breadth and thickness. Some examples of B C
points are tip of a compass, tip of a sharp pencil, etc.

Line
A line is a collection of points along an endless straight path. It has Maths Info
only length and no breadth. A line passing through two points A and An infinite number of lines can
←→ ←→
B is denoted by AB (read as line AB) or BA (read as line BA). be drawn through a given point.

A B

We can also denote a line by small letters like l, m, n, etc. The arrows Maths Info
on both sides of a line show that the line can be extended upto any
length and hence it is endless. A line can be straight or curved although Every line has infinite number
when we say ‘a line’ it means a straight line. Given below are some of points on it.
curved lines.

C
A B D

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