A set square is a flat triangle used to draw and check right angles. Line it up with a set square.
The two common ones are forty-five degrees and a thirty-sixty, which between them draw most angles. A set square is checked by flipping it over, which doubles any error.
1nounset squareA flat triangle used to draw and check right angles.
“The set square had a chipped corner and was useless.”
set square is a tool.
Practised in Tools & DIY