Congruent triangles (SAS)
I can appreciate and use the criteria by which triangles are congruent (SAS).
Congruent triangles (SAS)
I can appreciate and use the criteria by which triangles are congruent (SAS).
Lesson details
Key learning points
- By knowing two side lengths and the angle between them in the triangle and image, you can prove congruence.
- The angle between the sides must be the same in both object and image.
- The given sides must have the same multiplicative relationship.
Keywords
Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.
Common misconception
Pupils may believe that the angle doesn't need to be in between the two known sides.
Use the Geogebra files to demonstrate that more than one triangle can be formed at times, and therefore it does not guarantee congruence between two triangles.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
Loading...
Starter quiz
6 Questions
Exit quiz
6 Questions
∠BAF = ∠EFA -
as they are interior angles of a regular hexagon (= 120°)
∠GAF = ∠HFA -
as they are interior angles of a square (= 90°)
∠BAG = -
∠BAF − ∠GAF (= 30°)
∠HFE = -
∠EFA − ∠HFA (= 30°)
∠BAG = -
∠HFE
AB = AG = FH = FE -
as they are in regular polygons with shared edges