Carpentry Technique The following technique is used by

Chapter 1, Problem 40

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Carpentry Technique The following technique is used by carpenters to draw a 60 angle with a straightedge and a pair of compasses. Explain why this technique works. (Source: Hamilton, J. E. and M. S. Hamilton, Math to Build On, Construction Trades Press.) Draw a straight line segment, and mark a point near the midpoint. Now place the tip on the marked point, and draw a semicircle. Without changing the setting of the pair of compasses, place the tip at the right intersection of the line and the semicircle, and then mark a small arc across the semicircle. Finally, draw a line segment from the marked point on the original segment to the point where the arc crosses the semicircle. This will form a 60 angle with the original segment.