In construction, the precision used to build a structure directly influences the strength of the structure. In the Rocky Mountains, many houses’ roofs are built using trusses, which are strong enough to support the heavy load from snow, but light enough to build in a stockyard and transport to the construction site. Chris works in the stockyard. He has been told he needs to build a series of trusses for a new house using the pattern below. He has also been told the pattern may be inaccurate—so he needs to check and make sure the following features are all parallel, and adjust the pattern before starting. Describe the angles you would need to know to verify that BC, DE, and FG are all parallel to each other, and CD, EF, and GH are also parallel. What could be an appropriate measure for CDE? Be prepared to explain your choice for that angle. Use that measure to find all other angles involved.

1. What method(s) can Chris use to make sure the segments in the pattern are all parallel and that his new trusses are built precisely and strongly?
2. What method(s) can Chris’s boss use to verify the precision of the trusses Chris builds?
3. If you lived in a mountainous area with a lot of snow, how much leeway would you feel comfortable giving your home’s builders as they design and build your trusses? Why?
4. Identify any alternate interior angles, corresponding angles, and/or alternate exterior angles.