Ruler for dividing angle into three equal segments, has length direction lines provided on either side of central line, and two spaced apart cross direction lines

摘要

The transparent ruler has a black line (0.2 mm thick) running down the middle between its two ends, forming a central line. Thinner lines (0.1 mm thick) spaced apart by intervals of 5 mm extend the full length of the ruler, parallel to the central line, between the central line and one length edge of the ruler. The other half of the ruler is marked in the same way, except that the four lines measure only 25 mm in length from one end of the ruler. Two cross-direction lines (0.2 mm thick) extending at 90 deg. to the central line are located at distances of 5 and 25 mm from one end of the ruler.