Applying the criteria for congruence | Maths | Quizalize & Oak National Academy

Starter quiz

In triangle XYZ, angle $m$ is ______°.
- '32' ✓
Select the right-angled triangles. (Diagrams are not drawn accurately)
The square has a perimeter of 36 cm. The perimeter of the regular hexagon is ______cm.
- '54' ✓
All of these triangles are translations, rotations or reflections of each other. If they were cut out you could fit them exactly on of top of each other. You can say the triangles are ______.
- 'congruent' ✓
The quadrilaterals ABCD and EFGH are congruent and AD = 6 cm. Which edge on EFGH is also 6 cm?
- EF
- FG
- GH ✓
- EH
Complete the statement. Triangle ABC and triangle XYZ are ____________.
- congruent as the three interior angles are all the same.
- similar as the three interior angles are the same. ✓
- neither similar nor congruent.

Exit quiz

Which of the following are criteria for proving two triangles are congruent?
- AAA
- ASA ✓
- SAS ✓
- SSA
- RHS ✓
Triangle ABC and triangle DEF are congruent by __________.
- ASA ✓
- RHS
- SAS
- SSS
There is insufficient information to prove triangle ABC is congruent to triangle MNO by __________.
- ASA ✓
- RHS
- SAS
- SSS
Triangle KLM is __________ to triangle XYZ.
- definitely congruent
- definitely incongruent
- potentially congruent ✓
If you know that ABCD is a parallelogram, then __________ criteria for congruent triangles (ASA, RHS, SAS and SSS) can be used to show ABD and BDC are congruent.
- 0
- 1
- 2
- 3
- 4 ✓
Matching a, b, c and d to the correct statements to complete this congruence proof.
- a
  
  ⇔
  
  CD ✓
- b
  
  ⇔
  
  DE ✓
- c
  
  ⇔
  
  angle CDF ✓
- d
  
  ⇔
  
  angle CDE ✓

Worksheet

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Lesson Details

Key learning points

If two triangles are congruent, then one of the proven criteria must apply.
By stating the criteria (that you have already proven), you can prove congruence.
It is important to be clear why you know that two triangles are congruent.

Common misconception

Pupils may think they need to know the actual size or length to be able to prove congruence.

Remind pupils that if they can show that the corresponding angles or sides are the same length, then that is all that is needed. For example, if the corresponding edges are both edges of the same regular polygon, then they will be the same.

Keywords

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