GCSE · Trigonometry (sine & cosine rules)

The sine ruleExam-style questions

Why a/sin A = b/sin B holds in any triangle, choosing the sine rule by spotting a matching side–angle pair, turning it upside down to find an angle, and the ambiguous case where two triangles fit.

13 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 3Level 4Level 5
  1. 1
    In triangle ABCABC, angle A=52°A = 52°, angle B=71°B = 71° and a=8.4a = 8.4 cm.8.4 cmb52°71°ABCDiagram NOT accurately drawn

    Work out the length of bb. Give your answer correct to 1 decimal place.
    Level 3 · 3 marksTry it
  2. 2
    In triangle PQRPQR, p=12.6p = 12.6 cm, q=9.4q = 9.4 cm and angle P=48°P = 48°.

    Angle QQ is acute.

    Work out the size of angle QQ. Give your answer correct to 1 decimal place.
    Level 3 · 3 marksTry it
  3. 3
    In triangle ABCABC, angle A=61°A = 61°, angle C=47°C = 47° and c=10.5c = 10.5 cm.

    Work out the length of aa. Give your answer correct to 3 significant figures.
    Level 3 · 3 marksTry it
  4. 4
    In triangle PQRPQR, p=7.8p = 7.8 cm, angle P=42°P = 42° and angle R=66°R = 66°.

    Work out the length of rr. Give your answer correct to 3 significant figures.
    Level 3 · 3 marksTry it
  5. 5
    8.6 cm38°65°PQRDiagram NOT accurately drawn

    In triangle PQRPQR, PQ=8.6PQ = 8.6 cm, angle QPR=38°QPR = 38° and angle PQR=65°PQR = 65°.

    Work out the length of QRQR.

    Give your answer correct to 3 significant figures. (4 marks)
    Level 3 · 4 marksTry it

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