Rectangular protractor with bevelled edges. Side with protractor scales (0-180° by 1°, 180° by 10°) also has tables telling the central angle measure and the interior angle measure for polygons of sides 3-20. Other side has a scale for sines 0-90 degrees with transversals so measurements can be read to minutes. Also, a diagonal scale, 0-900 with 10 x 1000 grid.
