Basic Constructions
The tools in our geometry box are:
 Ruler
 Compass
 Divider
 Set squares
 Protractor
The description of each tool and its uses are given below:
Ruler:
A ruler is a flat and straightedged strip, whose one side is graduated into centimetres and the other into inches. A ruler is commonly called a scale. It is the most essential tool in geometry. It is used in all constructions.
The basic uses of a ruler are:
Measuring lengths of line segments
Drawing line segments
Compass:
A compass has two ends. One end holds a pointer, while the other end holds a pencil. It is also called a pair of compasses.
The basic uses of a compass are:
 Marking off equal lengths
 Drawing arcs
 Drawing circle
Divider:
A divider is a tool similar in shape to a compass. It has a pair of pointer ends.
The basic uses of a divider are:
 Comparing lengths of line segments
 Helping avoid positioning errors
 Taking accurate measurements
Set squares:
The two triangular tools in the geometry box are called set squares. One of the set square is an isosceles triangle with two angles measuring 45° each. The other set square is a scalene triangle with two angles measuring 30° and 60° each. The two perpendicular sides of either set square are graduated into centimetres.
The basic uses of set squares are:
 Drawing perpendicular lines
 Drawing parallel lines
Protractor:
A semicircular tool with degrees marked is called a protractor. The centre of the semicircle is called the midpoint of the protractor. This point helps as a reference point for the protractor. The horizontal line is called the base line or the straight edge of the protractor.
The basic uses of a protractor are:
 Measuring angles
 Drawing angles
The important points to be remembered while using the tools for construction are:
 Draw smooth and thin lines
 Mark points lightly
 Maintain tools or instruments with sharp pointers and fine edges
 Keep two pencils in the box. One is for drawing lines and marking points. The other is for using in the compass
Construction of Lines
Construction of Angels
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