What is it
KS3 geometry extends earlier shape work to angle facts in parallel lines, properties of polygons, congruence and similarity, and constructing accurate diagrams using a ruler, protractor and compasses.
Why it matters
Geometric reasoning — building a logical chain of angle facts to prove a result — is one of the purest forms of mathematical proof a student meets before A-Level, and it's heavily rewarded at GCSE.
Exam tip
Always state the angle fact or rule you're using alongside each step ('alternate angles are equal', 'angles in a triangle sum to 180°') — in reasoning questions, the justification often carries as many marks as the number itself.
Related topics
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