MA26-07 Maths Coming soon
Proving results using congruent triangles and angle facts
MA26-07
This lesson is coming soon.
In this lesson
Chain congruent-triangle reasoning with angle facts to prove a new geometric result, then use that result to find a further unknown.
What it covers
- Combining a congruent-triangle argument with known angle facts to derive a new result (e.g. base angles of an isosceles triangle are equal)
- Explicitly modelling the full two-stage pattern: prove the intermediate result, THEN use it to find something else in the diagram
- Recognising when a triangle needs to be split (e.g. by a perpendicular or bisector) to create the congruent pair needed for the proof
Key words
For: AQA GCSE 8300, Edexcel GCSE 1MA1, Eduqas GCSE C300, OCR GCSE J560
On the specification
| Board | Spec | Statement |
|---|---|---|
| AQA GCSE 8300 | G6 | Apply angle facts, triangle congruence, similarity and properties of quadrilaterals to conjecture and derive results about angles and sides, including Pythagoras’ theorem and the fact that the base angles of an isosceles triangle are equal, and use known results to obtain simple proofs |
| Edexcel GCSE 1MA1 | G6 | Apply angle facts, triangle congruence, similarity and properties of quadrilaterals to conjecture and derive results about angles and sides, including Pythagoras’ theorem and the fact that the base angles of an isosceles triangle are equal, and use known results to obtain simple proofs |
| Eduqas GCSE C300 | FG6 | Apply angle facts, triangle congruence, similarity and properties of quadrilaterals to conjecture and derive results about angles and sides, including Pythagoras' Theorem and the fact that the base angles of an isosceles triangle are equal, and use known results to obtain simple proofs |
| Eduqas GCSE C300 | HG6 | Apply angle facts, triangle congruence, similarity and properties of quadrilaterals to conjecture and derive results about angles and sides, including Pythagoras' Theorem and the fact that the base angles of an isosceles triangle are equal, and use known results to obtain simple proofs |
| OCR GCSE J560 | 9.02b | Apply congruent triangles in calculations and simple proofs. |
For teachers
This GCSE Maths lesson teaches proving results using congruent triangles and angle facts. By the end, students should be able to chain congruent-triangle reasoning with angle facts to prove a new geometric result, then use that result to find a further unknown. It works through two worked examples and the mistakes examiners report.