Page 165 - Start Up Mathematics_4

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Basic Geometry

Geometry is a branch of Mathematics that deals with points, lines, angles, shapes and solids.
To draw geometric figures accurately, we need a geometry box.

A geometry box contains the following things.
1. Two set squares

2. A protractor

3. A compass
4. A divider

5. A measuring scale

6. A pencil and an eraser
In this chapter we will learn about points, lines and angles.

Point

A point has no shape or size. It is just a dot made on paper. It is the smallest geometrical
shape. It has no length or breadth. We denote a point by a capital letter say A, B, C, etc. All
geometrical figures are made of points.
• • • •
A B C D are some examples of points.

Line Segment

Take two points say X and Y and join them using a ruler. X Y

The figure that you get is called a line segment. It is written as XY. X and Y are the end
points of the given line segment. A line segment can be vertical, horizontal or slanting. It
has a fixed length and cannot be extended from any side.

Ray

Extend the line segment XY from one end and put an arrow. The
figure that you get is called a ray. It is written with an arrow on X Y
top as XY , where X is its end point. A ray has one end point. It
cannot be measured as it can be extended to any length in one
direction.

Rays of the sun is a very good example of rays. They start from the
sun and can be extended to any length.

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