Back to Maths on Exam Trends
Triangles
High trendapprox. 8 marksSections C/D — similarity proofs and the basic proportionality theorem application.
CBSE 2027 — dates, rules and official papers →Ask the tutor1State the similarity criterion (AA / SAS / SSS) explicitly — proofs that skip this lose 1 mark.
Notesformulae · proofs · mind-map — one view
Learn the 4 conceptsteach yourself first, then practise each
Similar triangles — definition, examples and counter-examples1–2 marks Visual
Check BOTH conditions (equal corresponding angles AND proportional sides) before calling two triangles similar; congruent figures are similar, not the converse.
Similarity criteria (AA, SAS, SSS)2–3 marks Visual
Pick the right criterion to prove two triangles similar in one line.
Basic Proportionality Theorem (BPT)3–5 marks Visual
Apply when a line is parallel to one side of a triangle.
Converse of BPT (stated without proof)2–3 marks
A line dividing two sides of a triangle in the same ratio is parallel to the third side — use it to prove DE ∥ BC.
When you’re ready — practise or test the whole topic