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Grade 12 · Trigonometry
Compound & Double Angle Identities (Grade 12)
WORKSHEET
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  / 20

Answer all questions. Show all your working — marks are awarded for method as well as the final answer.

  1. 1
    Expand cos(A − B).
    (2)
  2. 2
    Expand sin(A + B).
    (2)
  3. 3
    Determine the exact value of cos75° without a calculator.
    (2)
  4. 4
    Determine the exact value of sin15° without a calculator.
    (2)
  5. 5
    Write down the three forms of cos2A.
    (2)
  6. 6
    If sinθ = 35 and θ is acute, determine cos2θ.
    (2)
  7. 7
    If sinθ = 35 and θ is acute, determine sin2θ.
    (2)
  8. 8
    Prove that sin2A1 + cos2A = tanA
    (2)
  9. 9
    Simplify 2 sin15° cos15°.
    (2)
  10. 10
    Why is sin(A + B) ≠ sinA + sinB?
    (2)
TOTAL: 20 marks
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