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SAI International School


                                               Class :  VI


           Mathematics


           Chapter - 5 – Understanding Elementary Shapes


           Lesson Note -5.3


           Subtopics:


                        Measuring angles using protractor
                         Perpendicular lines




                 The protractor:

                        We have a special instrument for measuring angles. It is called a protractor. Look at the
                         picture of a typical protractor with its important parts labelled.

























                 Measuring angle by a protractor:
                                Place your protractor on top of the angle. Make sure the origin is exactly on the
                  vertex of the angle, and the base line is exactly on top of one of the arms of the angle. Keep

                  adjusting the position of the protractor until the origin and the base line are exactly lined up.
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