| 摘要 |
A protractor for teaching aid includes a semicircular disk being provided along a curved section with angle marks and along a straight edge with length marks to form a main body of the protractor, and at a center with a locating hole or a locating bar; and at least one indicating strip being provided at two ends at one side with a short bar each, with a receiving hole correspondingly formed behind each short bar, and on one surface along a centerline with a central marker. The indicating strips may be rotatably connected at the short bars or the receiving holes to the locating hole or the locating bar, respectively, or rotatably connected end to end to form a polygon, so that the protractor has not only the function of measuring an angle, but also many other teaching functions.
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