ICSE Class 10 Mathematics: Similarity — Important Questions with Answers 2026

Short Answer Questions (2-3 Marks)

• Q: State the conditions for similarity of two triangles.
  Ans: Two triangles are similar if: (1) AAA Similarity: All three pairs of corresponding angles are equal. (2) SAS Similarity: One pair of corresponding angles is equal and the sides including this angle are proportional. (3) SSS Similarity: All three pairs of corresponding sides are proportional.
• Q: In △ABC, DE ∥ BC. AD = 3 cm, DB = 5 cm, AE = 4.5 cm. Find EC.
  Ans: By Basic Proportionality Theorem (Thales' theorem): AD/DB = AE/EC. 3/5 = 4.5/EC. EC = (5 × 4.5)/3 = 22.5/3 = 7.5 cm.
• Q: The areas of two similar triangles are 36 cm² and 64 cm². If a side of the smaller triangle is 12 cm, find the corresponding side of the larger triangle.
  Ans: Ratio of areas = (ratio of corresponding sides)². 36/64 = (12/x)². 9/16 = 144/x². x² = 144 × 16/9 = 256. x = 16 cm.

Exam Tips for This Chapter

• Revise all definitions and laws from Similarity — they are commonly asked as 1-2 mark questions
• Practice diagrams related to Similarity — neat labelled diagrams carry 2-3 marks
• For numericals, always show formula → substitution → answer with correct units
• Previous year analysis shows Similarity carries 8-12 marks in the board exam