On Tuesday 24 March 2009 02:24:53 Pat Naughtin wrote: > You may recall that I have worried about this issue in the past. It > appals me that the SI does not have a unit for angles that can be > conveniently used for designing and constructing buildings. There are > probably more angle measures done on the building sites of the world > than anywhere else in our societies. All that carpenters and plumbers > have — by default — is the old Babylonian degrees, minutes, and > seconds as radians have almost always been useless to them. My > recommendation some years ago was that the CIPM and the CGPM should > recognise that the initial unit of the metric system was the quadrant, > that this unit name could be reduced to the unit name quad, and that > and builders, sailors, and all of us could measure all of our angles > in quads (symbol q) and milliquads (symbol mq).
The problem with quads or gons is that 60 degrees, a common angle with the useful property that its cosine is 0.5, is an infinitely long decimal number of them. 45°, which is 50 gons, is commonly used for bay windows, but if two wings of a building are oblique to each other, the angle is sometimes 45° and sometimes 60°. There's no reason I can see for dividing the degree in 60, except tradition, and dividing it decimally would make arithmetic easier, but for dividing the quadrant by a multiple of 3, there is a reason. Pierre
