MA26-09 Maths Coming soon

Formal proofs using triangle and quadrilateral properties (Higher)

MA26-09

This lesson is coming soon.

Watch now instead: MA32-01 Mean, median, mode and range

In this lesson

Write a formal, structured proof of congruence or similarity, choosing the correct structure for each.

What it covers

Structuring a formal written proof (statement, reason, statement, reason, conclusion) using triangle and quadrilateral properties
Side-by-side comparison of what a congruence proof needs (equal sides/angles matched to SSS/SAS/ASA/RHS) versus what a similarity proof needs (equal angles, or side ratios, not raw lengths)
Producing a complete, correctly concluded chain of reasoning suitable for feeding into a larger geometric result

Key words

prove that triangle prove similar prove congruent formal proof stating your reasons

For: OCR GCSE J560

On the specification

Board	Spec	Statement
OCR GCSE J560	8.04a	Know the basic properties of isosceles, equilateral and right-angled triangles. Give geometrical reasons to justify these properties.
OCR GCSE J560	8.04b	Know the basic properties of the square, rectangle, parallelogram, trapezium, kite and rhombus. Give geometrical reasons to justify these properties.

For teachers

This GCSE Maths lesson teaches formal proofs using triangle and quadrilateral properties (Higher). By the end, students should be able to write a formal, structured proof of congruence or similarity, choosing the correct structure for each. It works through two worked examples and the mistakes examiners report.