SSS - GCSE Maths Definition

In GCSE Mathematics, 'SSS' is an abbreviation used in geometry, meaning 'side-side-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 the three sides of both triangles have the same lengths, 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 are of equal length by using geometric properties of triangles rather than measuring with a ruler.

Do note that the 'opposite' of this rule, which would be angle-angle-angle, is NOT a way of showing two triangles are congruent - two such triangles could be similar (one is an enlargement of the other, angles are unaffected by an enlargement).