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0580/42 May/Jun 2025, Question 13: Finding Missing Sides

Cambridge IGCSE Mathematics 0580 · Paper 42 (Extended) · Calculator · 4 marks

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The question, in short

Using two similar triangles ABC and PQR with AB = 9 cm, AC = 12 cm, BC = 16 cm and PQ = 6 cm, find a missing side and a prism volume.

Summarised in our own words. Use the official paper for the exact wording and the diagram.

Part (a) · 2 marks

Work out the length of PR, using the similarity of triangles ABC and PQR.

  1. 1Scale factor from ABC to PQR = 6/9 = 2/3
  2. 2PR = 12 × 2/3 = 8 cm

Answer8

Part (b) · 2 marks

Given the smaller prism has volume 1120 cm³, work out the volume of the larger prism.

  1. 1Length scale factor = 9/6 = 1.5, so volume scale factor = 1.5³ = 3.375
  2. 2Larger volume = 1120 × 3.375 = 3780 cm³

Answer3780

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Also searched as: 0580/42/M/J/25 · 0580_s25_qp_42 · 0580 s25 42 · question 13.
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