Each student is given an angle drawn on a plain sheet of paper, ruler, compass, scientific calculator, but no protractor. (An example) d = 8.7 cm. Do not adjust the compass Look at your constructed triangles \({\triangle}\text{ABC},~{\triangle}\text{DEF} Place the origin of the protractor at one end of the line. Place the compass on the vertex of the angle (point B). Angled bevel in place and tighten up fully to hold angle. segment. So let's try to do that. However, if you don't have a protractor handy, you can determine the size of an angle using the basic geometric principles of triangles. STEP 4 After you’ve marked the said angle, draw a line connecting the vertex and the marked point. It is, then, surprising that the modern protractor is barely over 200 years old.A protractor measures angles from a point, alo… Several different angle breeds, or types, exist. segment (CD) is the bisector of AB. You can click and drag the handles to change the angles and the values will updated. 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