The two acute angles of the isosceles square are 45 °. Two identical isosceles right triangle rulers can form a square or a larger isosceles right triangle. The two right-angle sides of an isosceles square are equal in length.

The most taboo thing about rulers is the scratching and blurring of the engraved value, so rulers become the most protected articles in stationery. The use of rulers should be correct. For example, it is better not to use plastic rulers when delimiting materials, which will easily be scratched. Many people will make a mistake, that is, they will draw the line very fast, and then they will run along the ruler because of the slippery characteristics of the ruler, which will make the value, so the speed is moderate.