Trigonometry and houses

Without Trig, your house would be lopsided.

Architects and contractors use trig to find the "pitch" of a roof while road constructors use the term "grade". To understand "pitch" and "slope" we must understand the trigonometric function tangent. When talking about the pitch of a roof, a fraction is used to describe it. For instance 11/18. For every 11 inches rise, there are 18 inches of run. Rise/Run or Opposite/Adjacent is the notation for tangent as well!


So if the full length of the "run" is 22 feet, lets calculate the full length of the rise, and then the angle of elevation.
11/18 = x/22, x = 36.
So if the angle of elevation is Rise/Run, then 36/22 is the slope! The tangent function works such, that if you plug in the angle of elevation, that we would get the slope. The inverse of the tangent function however will provide the angle if you provide the slope. So to find the angle of elevation, we plug our slope into the inverse tangent function.
tan^-1(36/22) = 58.6 degrees
reference:
http://jwilson.coe.uga.edu/EMAT6680Su09/King/Roofing/Application%20of%20%20Mathematics%20in%20Construction.htm