Saturday, March 19, 2011

Geometrical instruments box

1. Ruler
A Geometrical instruments box is a basic requirement for those who learn geometry. You have used the instruments in the geometry box in your previous classes. Let us recall their names and uses.

One edge of the ruler is graduated in centimeters and the other in inches. A ruler is used to draw lines and measure the length of the line segment.


2. Compass
Compass is used to draw a circle with a given measurement of its radius and a line segment. We can also construct angles of given measures with the compass.  There is a provision in the compass to insert a pencil.


3. Divider
It is used to measure the length of a line segment and to compare the lengths of two given line
segments.


4 and 5 A pair of Set – Squares
They are used to construct perpendicular lines and parallel lines. One set-square has
30° 60° 90° angles at the vertices and the other has 45° 45° 90° angles at the vertices.


6. Protractor
A protractor’s curved edge is graduated into 180 equal parts. Each part is equal to one degree.
The graduation starts from 0° on the right hand side and ends with 180° on the left hand side and viceversa.

A protractor is used to construct and to measure given angles.


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