Answer:
1. Their basic purpose is to show circular/cylindrical features in a drawing, which are found in abundance in mechanical parts. Common examples of such features include bolt holes, pins, discs, etc. Figure 1 shows how a centerline looks, characterized by its long-short-long alternating line pattern.
2.Line which shows where part is broken to reveal detail behind the part or to shorten a long continuous part. 3. They are very thin (size) , long-short-long kinds of lines. Dimension lines are thin and are used to show the actual size of an object. There are arrowheads at both end that terminate at the extension lines. Extension lines are also thin lines, showing the limits of dimensions.ng continuous part.
