This key facts covers Congruent vs Similar — Quick Comparison within Congruence for GCSE Mathematics. Revise Congruence in Geometry & Measures for GCSE Mathematics with 15 exam-style questions and 12 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 8 of 11 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Congruent vs Similar — Quick Comparison
| Property | Congruent | Similar |
|---|---|---|
| Same shape | Yes | Yes |
| Same size | Yes | Not necessarily |
| Angles equal | Yes | Yes |
| Sides equal | Yes (all) | Proportional (scale factor) |
| Scale factor | Always 1 | Any positive value |
Practice questions for Congruence
Which of the following is NOT a valid congruence condition for triangles?
When writing a congruence statement, such as triangle ABC ≅ triangle PQR, explain what it tells you about the sides and angles of the two triangles.
Quick recall flashcards
SAS Congruence Condition
Side-Angle-Side: Two sides and the INCLUDED angle (the angle between the two sides) are equal.
The angle MUST be between the two sides — if it is not included, SAS does not apply.
SSS Congruence Condition
Side-Side-Side: All three pairs of corresponding sides are equal.
If AB = DE, BC = EF, and AC = DF, then the triangles are congruent.
Fixing three side lengths determines the triangle completely.