How do you estimate the size of an angle in degrees?

Answer 1

Estimating is an art, but skilled craftsmen are often very good at it. In constructed sites angles are usually 90o or simple fraction of 90o (45o, 22.5o or 30o or 60o). Estimating these is simple, look at the angle, if it is less than 90o (less than the square angle formed by the edge of a book) ask yourself if it appears to be half that angle (45o) or half of that angle again (22.5o) which is the angle in 8 sided windows. An angle bigger than 45o is likely to be 60o, an angle smaller than 45o but bigger than 22.5o is likely to be 30o.

The estimation of angles of natural objects (trees etc) or of random drawn angles is done in the same way.