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Learning objective

Apply the sine and cosine rules to solve problems related to non-right-angled triangles, including those with obtuse angles and ambiguous cases. Use the formula for the area of a triangle, which is given as area = ab sin C.

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  • Practise with linked questions.
Cambridge IGCSE MathematicsExtended TrigonometrySupplement content

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Quick explanation

Apply the sine and cosine rules to solve problems related to non-right-angled triangles, including those with obtuse angles and ambiguous cases. Use the formula for the area of a triangle, which is given as area = ab sin C

  • This point belongs to Non-right-angled triangles, especially Non-right-angled triangles outcomes.
  • You need to be able to apply the sine and cosine rules to solve problems related to non-right-angled triangles, including those with obtuse angles and ambiguous cases. Use the formula for the area of a triangle, which is given as area = ab sin C.
  • The key ideas to know are Calculate, Determine, and Show.
  • Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

CalculateDetermineShowWork out

Why it matters

This objective helps connect Non-right-angled triangles outcomes to exam-style questions, flashcards, and revision notes for Non-right-angled triangles.

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Paper 2 structured question: Non-right-angled triangles

Paper 2Core or Extended Mathematics6 marks

Diagram Description

Triangle ABC

Triangle ABC has sides AB = 7 cm, AC = 10 cm, and angle BAC = 120°. Find the length of side BC and the area of the triangle.

Side/AngleValue
AB7 cm
AC10 cm
Angle BAC120°
  1. a

    Calculate the length of side BC.

    Aim for approximately 3 distinct marking points.

    [3]
  2. b

    Calculate the area of triangle ABC.

    Aim for approximately 3 distinct marking points.

    [3]
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