Congruent triangles (ASA and AAS) | Maths | Quizalize & Oak National Academy

Starter quiz

Which line segment has not been drawn to the same length as the other two?
The angle marked $x°$ is ______°.
- '73' ✓
The missing angle in triangle XYZ is ______°.
- '33' ✓
Triangle ABC is congruent to triangle XYZ, therefore YZ = ______ cm.
- '8.2' ✓
Triangle ABC and triangle XYZ are congruent, therefore ______ is 9.6 cm.
- 'YZ' ✓
All __________ are similar.
- squares ✓
- rectangles
- equilateral triangles ✓
- rhombi
- circle ✓

The criteria ASA (angle-side-angle) and AAS (angle-angle-side) are equivalent. True or false?
- True - if you know two angles in a triangle then you can calculate the third. ✓
- False - one is where you know the side between two angles and the other isn't.
Triangle ABC and triangle XYZ are congruent by AAS/ASA. Which angle in triangle XYZ is 46°?
- ∠YXZ
- ∠XZY ✓
- It doesn't matter
Match each triangle on the top row to the triangle on the bottom row that it is congruent to.
- a
  
  ⇔
  
  d ✓
- b
  
  ⇔
  
  f ✓
- c
  
  ⇔
  
  e ✓
Which of the following triangles is not guaranteed to be congruent to the other three triangles?
Which of these quadrilaterals can be split into two congruent triangles using one diagonal?
- square ✓
- rectangle ✓
- kite ✓
- trapezium
- parallelogram ✓
Complete this congruence proof. ∠ABD = ∠BDC as they are given in the diagram, BD is a shared edge and ∠ADB = ∠DBC as they are equal ______ angles, so triangle ABD and BDC are congruent by SAS.
- 'alternate' ✓

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By knowing two angles and a length in the triangle and image, you can prove congruence.
The angle pairs must be identical.
This rule is derived from the SAS criteria for congruence.

Pupils may struggle to spot congruent triangles if they only look for ASA.

Encourage pupils to add any further information to diagrams, like the third angle, before starting to prove congruence.

Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.