SAS - GCSE Maths Definition

In GCSE Mathematics, 'SAS' is an abbreviation used in geometry, meaning 'side-angle-side'. This allows us to compare two triangles to see if they are congruent (i.e. they are identical - same side lengths and same angle sizes). If two sides of both triangles have the same length, and the angle between those two sides in both triangles are equal, then the triangles are congruent. One may be a transformation of the other, but they are identical. In solving geometric problems, we can often show sides and/or angles are of equal size by using geometric properties of triangles rather than measuring with a ruler.