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4024/12 Oct/Nov 2020, Question 14: Volume of a Prism

Cambridge O Level Mathematics 4024 · Paper 12 (Non-calculator) · Non-calculator · 4 marks

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The question, in short

A net folds into a triangular prism; identify which vertices meet A and which edge meets DE, then use FH = 2 cm, GH = 2 cm and JH = 5 cm to find the prism's volume.

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

Part (a) · 1 mark

State which vertices of the net come together with vertex A when the net is folded into the prism.

  1. 1Folding the net, rectangle JKAB closes the prism so that edge AB meets edge DE, so A meets E
  2. 2Triangle FGH is the end face at A's end, so G also meets A
  3. 3Vertices joining with A: G and E

AnswerG and E

Part (b) · 1 mark

State which edge of the net coincides with edge DE once folded.

  1. 1DE and AB are the two free ends of the strip of rectangles, so they join
  2. 2Edge DE joins with AB

AnswerBA or AB

Part (c) · 2 marks

Given FH = 2 cm, GH = 2 cm and JH = 5 cm, calculate the volume of the triangular prism.

  1. 1Cross-section = right-angled triangle FGH: area = 1/2 × 2 × 2 = 2 cm²
  2. 2Volume = area of cross-section × length = 2 × 5
  3. 3= 10 cm³

Answer10

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