Writing About Rafter Tables

The following table is called a rafter table in the construction industry. The table is used by carpenters to calculate the length of rafters if you know the slope of a roof.

Roof Slope
Rafter
2 in 12
1.014
3 in 12
1.031
4 in 12
1.054
5 in 12
1.083
6 in 12
1.118
7 in 12
1.158
8 in 12
1.202
9 in 12
1.25
10 in 12
1.302
11 in 12
1.357
12 in 12
1.413
Mathematics:
Show the calculations used to generate the numbers in the second column.
Technical Writing:
Write out the process for using the rafter table.
Illustrate your process with one example.