Chap 11- Constructions

CONSTRUCTIONS

IMPORTANT POINTS TO REMEMBER

·       To draw geometrical figure accurately some basic geometrical instruments are needed.

                                                      i.     A graduated scale, on whose one edge marked centimeters  and millimeters and on the other side inches and their parts.

                                                     ii.    A pair of set-squares, one with angle 60° and 30° and other with angles 45° and 45° .

                                                    iii.    A pair of dividers (or divider) with adjustments.

                                                   iv.     A pair of compasses (or a compass) with provision of filling a pencil at one end.

                                                     v.     A protractor.

Normally, all these instruments are needed in drawing a geometrical figure, such as a triangle, a circle, a quadrilateral, a polygon etc. with given measurements. But a geometrical construction is the process of drawing a geometrical  figure using only tow instruments an use graduated ruler, also called a straight edge and compass. In construction where measurements are also required you may use graduated scale and protractor also.