Architectural draughting set square - has right angled triangular shape with sides subtending right angle in ratio giving golden section

摘要

The draughtsman's set square is used in the architectural field for direct derivation of the 'gold section' giving building elements harmonious proportions. It has a right angled triangular shape with the remaining angles (ABC & ACB) subtending 58 degrees 16' 57.09" and 31 degrees 43' 2.91", the ratio of the sides (AC,AB) subtending the right angle being 1:0.618034.