There are two standard triangles. One has angles of 30 °_600_90 °
and is known as the 30-60 triangle. The other has angles of 45 °_45
°90 ° and is known as the 45 ° triangle.
Some drafters prefer to use triangles in place of a vertical
drafting machine scale. The machine protractor or the triangle can be
used to make angled lines. Drafters who use parallel bars rather than
draffing machines also use triangles to make vertical and angled
lines.