A protractor is used to draw and measure angles. An angle is the amount of turn between two lines. Angles are measured in degrees with the symbol °. Angles can be labelled with 3 letters (eg DEF ...

A diagonal scale and scales for dividing the inch into 10, 12, and 16 parts appear in the interior of the protractor. A celluloid arm is attached at the vertex of the protractor. Users were to set ...

The disc is marked: SAFE-T PROTRACTOR ™. It directs students to look at the upper, black numbers for angles facing left and at the lower, red numbers for angles facing right. A scale of 11 centimeters ...